<PAGE>   1
                                                                     EXHIBIT 4.3
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                                NRG ENERGY, INC.


                                       AND


                            ------------------------,
                           AS PURCHASE CONTRACT AGENT


                              --------------------
                           PURCHASE CONTRACT AGREEMENT
                              --------------------

                          DATED AS OF          , 2001
                                     ----------















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<PAGE>   2

                                TABLE OF CONTENTS

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RECITALS............................................................................................1

ARTICLE I
Definitions and Other Provisions
of General Applications.............................................................................1
Section 1.1.      Definitions.......................................................................1
Section 1.2.      Compliance Certificates and Opinions.............................................16
Section 1.3.      Form of Documents Delivered to Agent.............................................17
Section 1.4.      Acts of Holders; Record Dates....................................................18
Section 1.5.      Notices..........................................................................19
Section 1.6.      Notice to Holders; Waiver........................................................20
Section 1.7.      Effect of Headings and Table of Contents.........................................21
Section 1.8.      Successors and Assigns...........................................................21
Section 1.9.      Separability Clause..............................................................21
Section 1.10.     Benefits of Agreement............................................................21
Section 1.11.     Governing Law....................................................................22
Section 1.12.     Legal Holidays...................................................................22
Section 1.13.     Counterparts.....................................................................22
Section 1.14.     Inspection of Agreement..........................................................23

ARTICLE II
Certificate Forms..................................................................................23
Section 2.1.      Forms of Certificates Generally..................................................23
Section 2.2.      Form of Agent's Certificate of Authentication....................................24

ARTICLE III
The Securities.....................................................................................24
Section 3.1.      Title and Terms; Denominations...................................................24
Section 3.2.      Rights and Obligations Evidenced by the Certificates.............................25
Section 3.3.      Execution, Authentication, Delivery and Dating...................................26
Section 3.4.      Temporary Certificates...........................................................26
Section 3.5.      Registration; Registration of Transfer and Exchange..............................27
Section 3.6.      Book-Entry Interests.............................................................29
Section 3.7.      Notices to Holders...............................................................30
Section 3.8.      Appointment of Successor Clearing Agency.........................................30
Section 3.9.      Definitive Certificates..........................................................30
Section 3.10.     Mutilated, Destroyed, Lost and Stolen Certificates...............................30
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<TABLE>
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Section 3.11.     Persons Deemed Owners............................................................32
Section 3.12.     Cancellation.....................................................................32
Section 3.13.     Establishment of Treasury Units..................................................33
Section 3.14.     Reestablishment of Corporate Units...............................................35
Section 3.15.     Transfer of Collateral upon Occurrence of Termination Event......................37
Section 3.16.     No Consent to Assumption.........................................................38

ARTICLE IV
The Debentures.....................................................................................38
Section 4.1.      Payment of Distribution; Rights to Distributions Preserved;
                                    Distribution Rate Reset; Notice................................38
Section 4.2.      Notice and Voting................................................................40
Section 4.3.      Tax Event Redemption.............................................................41

ARTICLE V
The Purchase Contracts.............................................................................42
Section 5.1.      Purchase of Shares of Common Stock...............................................42
Section 5.2.      [Reserved].......................................................................44
Section 5.3.      Initial Remarketing..............................................................44
Section 5.4.      Payment of Purchase Price........................................................45
Section 5.5.      Issuance of Shares of Common Stock...............................................49
Section 5.6.      Adjustment of Settlement Rate....................................................50
Section 5.7.      Notice of Adjustments and Certain Other Events...................................58
Section 5.8.      Termination Event; Notice........................................................59
Section 5.9.      Early Settlement.................................................................59
Section 5.10.     No Fractional Shares.............................................................61
Section 5.11.     Charges and Taxes................................................................62

ARTICLE VI
Remedies...........................................................................................62
Section 6.1.      Unconditional Right of Holders to Purchase Common Stock..........................62
Section 6.2.      Restoration of Rights and Remedies...............................................62
Section 6.3.      Rights and Remedies Cumulative...................................................63
Section 6.4.      Delay or Omission Not Waiver.....................................................63
Section 6.5.      Undertaking for Costs............................................................63
Section 6.6.      Waiver of Stay or Extension Laws.................................................64
ARTICLE VII
The Agent..........................................................................................64
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Section 7.1.      Certain Duties and Responsibilities..............................................64
Section 7.2.      Notice of Default................................................................65
Section 7.3.      Certain Rights of Agent..........................................................65
Section 7.4.      Not Responsible for Recitals or Issuance of Securities...........................66
Section 7.5.      May Hold Securities..............................................................66
Section 7.6.      Money Held in Custody............................................................67
Section 7.7.      Compensation and Reimbursement...................................................67
Section 7.8.      Corporate Agent Required; Eligibility............................................68
Section 7.9.      Resignation and Removal; Appointment of Successor................................68
Section 7.10.     Acceptance of Appointment by Successor...........................................70
Section 7.11.     Merger, Conversion, Consolidation or Succession to Business......................70
Section 7.12.     Preservation of Information; Communications to Holders...........................71
Section 7.13.     No Obligations of Agent..........................................................71
Section 7.14.     Tax Compliance...................................................................71

ARTICLE VIII
Supplemental Agreements............................................................................72
Section 8.1.      Supplemental Agreements Without Consent of Holders...............................72
Section 8.2.      Supplemental Agreements with Consent of Holders..................................73
Section 8.3.      Execution of Supplemental Agreements.............................................74
Section 8.4.      Effect of Supplemental Agreements................................................74
Section 8.5.      Reference to Supplemental Agreements.............................................75

ARTICLE IX
Consolidation, Merger, Sale or Conveyance..........................................................75
Section 9.1.      Covenant Not to Merge, Consolidate, Sell or Convey Property Except
                  Under Certain Conditions.........................................................75
Section 9.2.      Rights and Duties of Successor Corporation.......................................76
Section 9.3.      Opinion of Counsel Given to Agent................................................76

ARTICLE X
Covenants..........................................................................................77
Section 10.1.     Performance Under Purchase Contracts.............................................77
Section 10.2.     Maintenance of Office or Agency..................................................77
Section 10.3.     Company to Reserve Common Stock..................................................78
Section 10.4.     Covenants as to Common Stock.....................................................78
</TABLE>

EXHIBIT A         Form of Corporate Units Certificate

                                       iii
<PAGE>   5

                                                                 Page
                                                                 ----
EXHIBIT B         Form of Treasury Units Certificate
EXHIBIT C         Instruction From Purchase Contract Agent
                  to Collateral Agent
EXHIBIT D         Instruction to Purchase Contract Agent
EXHIBIT E         Notice to Settle by Separate Cash









                                       iv
<PAGE>   6

         PURCHASE CONTRACT AGREEMENT, dated as of _________, 2001 between NRG
Energy, Inc., a Delaware corporation (the "Company"), and _____________________,
a _____________ corporation, acting as purchase contract agent for the Holders
of Securities from time to time (the "Agent").


                                    RECITALS

         The Company has duly authorized the execution and delivery of this
Agreement and the Certificates evidencing the Securities.

         All things necessary to make the Purchase Contracts, when the
Certificates are executed by the Company and authenticated, executed on behalf
of the Holders and delivered by the Agent, as provided in this Agreement, the
valid obligations of the Company, and to constitute these presents a valid
agreement of the Company, in accordance with its terms, have been done.


                                   WITNESSETH:

         For and in consideration of the premises and the purchase of the
Securities by the Holders thereof, it is mutually agreed as follows:


                                    ARTICLE I

                        Definitions and Other Provisions
                             of General Applications

Section 1.1. Definitions.

         For all purposes of this Agreement, except as otherwise expressly
provided or unless the context otherwise requires:

         (a) the terms defined in this Article have the meanings assigned to
them in this Article and include the plural as well as the singular; and nouns
and pronouns of the masculine gender include the feminine and neuter genders;



<PAGE>   7
         (b) all accounting terms not otherwise defined herein have the meanings
assigned to them in accordance with generally accepted accounting principles in
the United States;

         (c) the words "herein," "hereof" and "hereunder" and other words of
similar import refer to this Agreement as a whole and not to any particular
Article, Section or other subdivision;

         (d) the following terms have the meanings given to them in this Section
1.1(d).

         "Act" when used with respect to any Holder, has the meaning specified
in Section 1.4.

         "Affiliate" has the same meaning as given to that term in Rule 405 of
the Securities Act of 1993, as amended, as is in effect on the date hereof.

         "Agent" means the Person named as the "Agent" in the first paragraph of
this instrument until a successor Agent shall have become such pursuant to the
applicable provisions of this Agreement, and thereafter "Agent" shall mean such
Person.

         "Agreement" means this instrument as originally executed or as it may
from time to time be supplemented or amended by one or more agreements
supplemental hereto entered into pursuant to the applicable provisions hereof.

         "Applicable Market Value" has the meaning specified in Section 5.1.

         "Applicable Ownership Interest" means, with respect to a Corporate Unit
and the Treasury Securities in the Treasury Portfolio, (A) a 1/40, or 2.5%,
undivided beneficial ownership interest in a $1,000 principal or interest amount
of a principal or interest strip in a U.S. Treasury Security included in such
Treasury Portfolio which matures on or prior to ____________, 2004 and (B) for
the scheduled interest payment date on the Debentures that occurs on the
Purchase Contract Settlement Date, in the case of a Successful Initial
Remarketing, or after the Tax Event Redemption Date and on or before the
Purchase Contract Settlement Date, in the case of a Tax Event Redemption, a ___%
undivided beneficial ownership interest in a $1,000 face amount of such U.S.
Treasury Security which is a principal or interest strip maturing on such
interest payment date.


                                       2
<PAGE>   8

         "Applicable Principal Amount" means the aggregate principal amount of
the Debentures which are components of Corporate Units on the Initial
Remarketing Date.

         "Authorized Newspaper" means a daily newspaper, in the English
language, customarily published on each day that is a Business Day in The City
of New York, whether or not published on days that are Legal Holidays, and of
general circulation in The City of New York. The Authorized Newspaper for the
purposes of the Reset Announcement Date is currently anticipated to be The Wall
Street Journal.

         "Bankruptcy Code" means title 11 of the United States Code, or any
other law of the United States that from time to time provides a uniform system
of bankruptcy laws.

         "Beneficial Owner" means, with respect to a Book-Entry Interest, a
Person who is the owner of such Book-Entry Interest as reflected on the books of
the Clearing Agency or on the books of a Person maintaining an account with such
Clearing Agency (directly as a Clearing Agency Participant or as an indirect
participant, in each case in accordance with the rules of such Clearing Agency).

         "Board of Directors" means the board of directors of the Company or a
duly authorized committee of that board.

         "Board Resolution" means one or more resolutions of the Board of
Directors, a copy of which has been certified by the Secretary or an Assistant
Secretary of the Company to have been duly adopted by the Board of Directors and
to be in full force and effect on the date of such certification and delivered
to the Agent.

         "Book-Entry Interest" means a beneficial interest in a Global
Certificate, ownership and transfers of which shall be maintained and made
through book entries by a Clearing Agency as described in Section 3.6.

         "Business Day" means any day other than a Saturday, a Sunday or any
other day on which banking institutions in New York City (in the State of New
York) are permitted or required by any applicable law to close.

         "Cash Settlement" has the meaning set forth in Section 5.4(a)(i).

         "Certificate" means a Corporate Units Certificate or a Treasury Units
Certificate.


                                       3
<PAGE>   9

         "Class A Common Stock" means the Class A Common Stock, $0.01 par value,
of the Company.

         "Clearing Agency" means an organization registered as a "Clearing
Agency" pursuant to Section 17A of the Exchange Act that is acting as a
depositary for the Securities and in whose name, or in the name of a nominee of
that organization, shall be registered a Global Certificate and which shall
undertake to effect book entry transfers and pledges of the Securities.

         "Clearing Agency Participant" means a broker, dealer, bank, other
financial institution or other Person for whom from time to time the Clearing
Agency effects book entry transfers and pledges of securities deposited with the
Clearing Agency.

         "Closing Price" has the meaning specified in Section 5.1.

         "Collateral" has the meaning specified in Section 2.1 of the Pledge
Agreement.

         "Collateral Agent" means _______________, as Collateral Agent under the
Pledge Agreement until a successor Collateral Agent shall have become such
pursuant to the applicable provisions of the Pledge Agreement, and thereafter
"Collateral Agent" shall mean the Person who is then the Collateral Agent
thereunder.

         "Collateral Substitution" has the meaning specified in Section 3.13.

         "Common Equity Securities" means shares of a class of stock of the
Company that is not entitled to priority over any other class of stock of the
Company in the payment of dividends or with respect to rights upon the
liquidation, dissolution or winding up of the Company.

         "Common Stock" means the Common Stock, $0.01 par value, of the Company.

         "Company" means the Person named as the "Company" in the first
paragraph of this instrument until a successor shall have become such pursuant
to the applicable provision of this Agreement, and thereafter "Company" shall
mean such successor.

                                       4
<PAGE>   10

         "Corporate Trust Office" means the principal corporate trust office of
the Agent at which, at any particular time, its corporate trust business shall
be administered, which office at the date hereof is located at
____________________________.

         "Corporate Units" means the collective rights and obligations of a
Holder of a Corporate Units Certificate in respect of a Debenture or an
appropriate Applicable Ownership Interest of the Treasury Portfolio, as the case
may be, subject in each case to the Pledge thereof, and the related Purchase
Contract.

         "Corporate Units Certificate" means a certificate evidencing the rights
and obligations of a Holder in respect of the number of Corporate Units
specified on such certificate.

         "Corporate Units Register" and "Corporate Units Registrar" have the
respective meanings specified in Section 3.5.

         "Coupon Rate" means the percentage rate per annum at which each
Debenture will bear interest initially.

         "Current Market Price" has the meaning specified in Section 5.6(a)(8).

         "Debentures" means the series of debentures of the Company designated
the ___% Senior Debentures due ____________, 2006, to be issued under the
Indenture as of the date hereof.

         "Depositary" means, initially, DTC until another Clearing Agency
becomes its successor.

         "DTC" means The Depository Trust Company, the initial Clearing Agency.

         "Early Settlement" has the meaning specified in Section 5.9(a).

         "Early Settlement Amount" has the meaning specified in Section 5.9(a).

         "Early Settlement Date" has the meaning specified in Section 5.9(a).

         "Early Settlement Rate" has the meaning specified in Section 5.9(b).


                                       5
<PAGE>   11

         "Exchange Act" means the Securities Exchange Act of 1934 and any
statute successor thereto, in each case as amended from time to time, and the
rules and regulations promulgated thereunder.

         "Expiration Date" has the meaning specified in Section 1.4.

         "Expiration Time" has the meaning specified in Section 5.6(a)(6).

         "Failed Initial Remarketing" has the meaning specified in Section 5.3.

         "Failed Secondary Remarketing" has the meaning specified in Section
5.4(b).

         "Global Debenture Certificate" means a certificate evidencing the
respective rights and obligations of Holders in respect of the number of
Debentures specified on such certificate and which is registered in the name of
a Clearing Agency or a nominee thereof.

         "Global Certificate" means a Certificate that evidences all or part of
the Securities and is registered in the name of a Depositary or a nominee
thereof.

         "Holder," when used with respect to a Security, means the Person in
whose name the Security evidenced by a Corporate Units Certificate and/or
Treasury Units Certificate is registered in the related Corporate Units Register
and/or Treasury Units Register, as the case may be.

         "Indenture" means the Indenture dated as of ________, 2001 between the
Company and the Indenture Trustee, as amended and supplemented by the First
Supplemental Indenture dated as of _________, 2001 between the Company and the
Indenture Trustee.

         "Indenture Trustee" means __________________, a __________ corporation,
as trustee under the Indenture, or any successor thereto.

         "Initial Remarketing" has the meaning specified in Section 5.3.

         "Initial Remarketing Date" means the third business day immediately
preceding ___________, 2003.

         "Issuer Order" or "Issuer Request" means a written order or request
signed in the name of the Company by its Chairman of the Board, its President or
a Vice

                                       6
<PAGE>   12

President and by its Chief Financial Officer, its Treasurer, an Assistant
Treasurer, its Secretary or an Assistant Secretary, and delivered to the Agent.

         "NYSE" has the meaning specified in Section 5.1.

         "New York Office" shall have the meaning set forth in Section 10.2

         "Officer's Certificate" means a certificate of the Company signed on
its behalf by the Chairman of the Board, the President, any Vice President, the
Treasurer, any Assistant Treasurer, the Secretary or any Assistant Secretary of
the Company and delivered to the Agent.

         "Opinion of Counsel" means an opinion in writing signed by legal
counsel, who may be an employee of or counsel to the Company or an Affiliate and
who shall be reasonably acceptable to the Agent.

         "Outstanding Securities," with respect to the Corporate Units or
Treasury Units, means, as of the date of determination, all Corporate Units or
Treasury Units, as the case may be, evidenced by Certificates theretofore
authenticated, executed and delivered under this Agreement, except:

                  (i)   If a Termination Event has occurred, (A) Treasury Units
         for which the Stated Amount of Treasury Securities has been theretofore
         deposited with the Agent in trust for the Holders of such Treasury
         Units and (B) Corporate Units for which the Stated Amount of the
         related Debentures or the appropriate Applicable Ownership Interest of
         the Treasury Portfolio, as the case may be, has been theretofore
         deposited with the Agent in trust for the Holders of such Corporate
         Units;

                  (ii)  Corporate Units or Treasury Units evidenced by
         Certificates theretofore cancelled by the Agent or delivered to the
         Agent for cancellation or deemed cancelled pursuant to the provisions
         of this Agreement; and

                  (iii) Corporate Units or Treasury Units evidenced by
         Certificates in exchange for or in lieu of which other Certificates
         have been authenticated, executed on behalf of the Holder and delivered
         pursuant to this Agreement, other than any such Certificate in respect
         of which there shall have been presented to the Agent proof
         satisfactory to it that such Certificate is held by a bona fide
         purchaser in whose hands the Corporate Units or Treasury Units
         evidenced by such Certificate are valid obligations of the Company;

                                       7
<PAGE>   13

provided, however, that in determining whether the Holders of the requisite
number of the Corporate Units or Treasury Units have given any request, demand,
authorization, direction, notice, consent or waiver hereunder, Corporate Units
or Treasury Units owned by the Company or any Affiliate of the Company shall be
disregarded and deemed not to be outstanding, except that, in determining
whether the Agent shall be protected in relying upon any such request, demand,
authorization, direction, notice, consent or waiver, only Corporate Units or
Treasury Units which a Responsible Officer of the Agent knows to be so owned
shall be so disregarded. Corporate Units or Treasury Units so owned which have
been pledged in good faith may be regarded as Outstanding Securities if the
pledgee establishes to the satisfaction of the Agent the pledgee's right so to
act with respect to such Corporate Units or Treasury Units and that the pledgee
is not the Company or any Affiliate of the Company.

         "Payment Date" means each _________, _________, _________ and
_________, commencing ___________, 2001.

         "Person" means a legal person, including any individual, corporation,
estate, partnership, joint venture, association, joint-stock company, limited
liability company, trust, unincorporated association or government or any agency
or political subdivision thereof or any other entity of whatever nature.

         "Permitted Investments" has the meaning set forth in Section 1 of the
Pledge Agreement.

         "Pledge" means the pledge under the Pledge Agreement of the Debentures
or the appropriate Applicable Ownership Interest of the Treasury Portfolio, as
the case may be, and of the Treasury Securities, in each case constituting a
part of the Securities.

         "Pledge Agreement" means the Pledge Agreement, dated as of the date
hereof, by and among the Company, the Collateral Agent and the Agent, on its own
behalf and as attorney-in-fact for the Holders from time to time of the
Securities, as the same may hereafter be amended in accordance with the terms
thereof.

         "Predecessor Certificate" means a Predecessor Corporate Units
Certificate or a Predecessor Treasury Units Certificate.

         "Predecessor Corporate Units Certificate" of any particular Corporate
Units Certificate means every previous Corporate Units Certificate evidencing
all or a


                                       8
<PAGE>   14

portion of the rights and obligations of the Company and the Holder under the
Corporate Units evidenced thereby; and, for the purposes of this definition, any
Corporate Units Certificate authenticated and delivered under Section 3.10 in
exchange for or in lieu of a mutilated, destroyed, lost or stolen Corporate
Units Certificate shall be deemed to evidence the same rights and obligations of
the Company and the Holder as the mutilated, destroyed, lost or stolen Corporate
Units Certificate.

         "Predecessor Treasury Units Certificate" of any particular Treasury
Units Certificate means every previous Treasury Units Certificate evidencing all
or a portion of the rights and obligations of the Company and the Holder under
the Treasury Units evidenced thereby; and, for the purposes of this definition,
any Treasury Units Certificate authenticated and delivered under Section 3.10 in
exchange for or in lieu of a mutilated, destroyed, lost or stolen Treasury Units
Certificate shall be deemed to evidence the same rights and obligations of the
Company and the Holder as the mutilated, destroyed, lost or stolen Treasury
Units Certificate.

         "Primary Treasury Dealer" means a primary U.S. government securities
dealer in The City of New York.

         "Proceeds" has the meaning set forth in Section 1 of the Pledge
Agreement.

         "Purchase Contract," when used with respect to any Security, means the
contract forming a part of such Security and obligating the Company to (i) sell
and the Holder of such Security to purchase Common Stock on the terms and
subject to the conditions set forth in Article Five hereof.

         "Purchase Contract Settlement Date" means _______________, 2004.

         "Purchase Contract Settlement Fund" has the meaning specified in
Section 5.5.

         "Purchase Price" has the meaning specified in Section 5.1.

         "Purchased Shares" has the meaning specified in Section 5.6(a)(6).

         "Quotation Agent" means (i) Merrill Lynch Government Securities, Inc.
and its respective successors, provided, however, that if the foregoing shall
cease to be a


                                       9
<PAGE>   15

Primary Treasury Dealer, the Sponsor shall substitute therefor another Primary
Treasury Dealer or (ii) any other Primary Treasury Dealer selected by the
Sponsor.

         "Recapitalization Transaction" has the meaning specified in Section
5.6(a)(7).

         "Record Date" for the distribution payable in respect of the Debentures
or the Applicable Ownership Percentage of the Treasury Portfolio payable on any
Payment Date means the first day of the month in which the relevant Payment Date
occurs.

         "Redemption Amount" mean, for each Debenture, the product of (i) the
principal amount of such Debenture and (ii) a fraction whose numerator is the
applicable Treasury Portfolio Purchase Price and whose denominator is the
applicable Tax Event Redemption Principal Amount.

         "Redemption Price" means the redemption price per Debenture equal to
the Redemption Amount plus any accrued and unpaid interest on such Debenture to
the date of redemption.

         "Register" means the Corporate Units Register and the Treasury Units
Register.

         "Registrar" means the Corporate Units Registrar and the Treasury Units
Registrar.

         "Remarketing Agent" has the meaning specified in Section 5.3.

         "Remarketing Agreement" means the Remarketing Agreement dated as of
________, 2001 by and among the Company, the Remarketing Agent and the Purchase
Contract Agent.

         "Remarketing Fee" has the meaning specified in Section 5.3.

         "Reorganization Event" has the meaning specified in Section 5.6(c).

         "Reset Agent" means a nationally recognized investment banking firm
chosen by the Company to determine the Reset Rate. It is currently anticipated
that Merrill Lynch, Pierce, Fenner & Smith Incorporated will act in such
capacity.

         "Reset Announcement Date" means, in the case of the Reset Rate to be
determined on the Initial Remarketing Date, the tenth Business Day immediately


                                       10
<PAGE>   16

preceding __________________, 2003 and, in the case of the Reset Rate to be
determined on the Secondary Remarketing Date, the tenth Business Day immediately
preceding the Purchase Contract Settlement Date.

         "Reset Rate" means the interest rate per annum (to be determined by the
Reset Agent), equal to the sum of (X) the Reset Spread and (Y) the rate of
interest on (1) in the case of the Reset Rate to be determined on the Initial
Remarketing Date, the Two and One-Quarter Year Benchmark Treasury in effect on
the Initial Remarketing Date or (2) in the case of the Reset Rate to be
determined on the Secondary Remarketing Date, the Two-Year Benchmark Treasury in
effect on the Secondary Remarketing Date.

         "Reset Spread" means (a) in the case of the Reset Rate to be determined
on the Initial Remarketing Date, a spread amount to be determined by the Reset
Agent on the applicable Reset Announcement Date as the appropriate spread so
that the Reset Rate will be the interest rate that the Debentures should bear in
order for the Applicable Principal Amount of Debentures to have an approximate
aggregate market value of 100.5% of the Treasury Portfolio Purchase Price on the
Initial Remarketing Date and (b) in the case of the Reset Rate to be determined
on the Secondary Remarketing Date, a spread amount determined by the Reset Agent
on the applicable Reset Announcement Date as the appropriate spread so that the
Reset Rate will be the interest rate that the Debentures should bear in order
for the Debentures to have an approximate market value of 100.5% of their
principal amount on the Secondary Remarketing Date.

         "Responsible Officer," when used with respect to the Agent, means any
officer of the Agent assigned by the Agent to administer its corporate trust
matters.

         "Secondary Remarketing" has the meaning specified in Section 5.4(b).

         "Secondary Remarketing Date" means the third business day immediately
preceding the Purchase Contract Settlement Date.

         "Security" means a Corporate Unit or a Treasury Unit.

         "Settlement Rate" has the meaning specified in Section 5.1.

         "Stated Amount" means $25.

         "Successful Initial Remarketing" has the meaning specified in Section
5.3.


                                       11
<PAGE>   17

         "Successful Secondary Remarketing" has the meaning specified in Section
5.4(b).

         "Tax Event" means the receipt by the Company of an opinion of a
nationally recognized independent tax counsel experienced in such matters to the
effect that, as a result of (a) any amendment to, or change (including any
announced proposed change) in, the laws (or any regulations thereunder) of the
United States or any political subdivision or taxing authority thereof or
therein affecting taxation, (b) any amendment to or change in an interpretation
or application of such laws or regulations by any legislative body, court,
governmental agency or regulatory authority or (c) any interpretation or
pronouncement that provides for a position with respect to such laws or
regulations that differs from the generally accepted position on the date the
Debentures are issued, which amendment, change or proposed change is effective
or which interpretation or pronouncement is announced on or after the date of
the first issuance of Debentures under the Indenture, there is more than an
insubstantial risk that interest payable by the Company on the Debentures would
not be deductible, in whole or in part, by the Company for United States federal
income tax purposes.

         "Tax Event Redemption" means, if a Tax Event shall occur and be
continuing, the redemption of the Debentures, at the option of the Company, in
whole but not in part, on not less than 30 days nor more than 60 days notice.

         "Tax Event Redemption Principal Amount" means either (i) if the Tax
Event Redemption Date occurs prior to ______________, 2003 or, in the event of a
Failed Initial Remarketing, prior to the Purchase Contract Settlement Date, the
aggregate principal amount of the Debentures which are components of Corporate
Units on the Tax Event Redemption Date or (ii) if the Tax Event Redemption Date
occurs on or after _________________, 2003 or, in the event of a Failed Initial
Remarketing, on or after the Purchase Contract Settlement Date, the aggregate
principal amount of the Debentures outstanding on such Tax Event Redemption
Date.

         "Tax Event Redemption Date" means the date upon which a Tax Event
Redemption is to occur.

         "Termination Date" means the date, if any, on which a Termination Event
occurs.

         "Termination Event" means the occurrence of any of the following
events: (i) at any time on or prior to the Purchase Contract Settlement Date, a
judgment, decree



                                       12
<PAGE>   18

or court order shall have been entered granting relief under the Bankruptcy
Code, adjudicating the Company to be insolvent, or approving as properly filed a
petition seeking reorganization or liquidation of the Company or any other
similar applicable Federal or State law, and, unless such judgment, decree or
order shall have been entered within 60 days prior to the Purchase Contract
Settlement Date, such decree or order shall have continued undischarged and
unstayed for a period of 60 days; or (ii) at any time on or prior to the
Purchase Contract Settlement Date, a judgment, decree or court order for the
appointment of a receiver or liquidator or trustee or assignee in bankruptcy or
insolvency of the Company or of its property, or for the winding up or
liquidation of its affairs, shall have been entered, and, unless such judgment,
decree or order shall have been entered within 60 days prior to the Purchase
Contract Settlement Date, such judgment, decree or order shall have continued
undischarged and unstayed for a period of 60 days, or (iii) at any time on or
prior to the Purchase Contract Settlement Date the Company shall file a petition
for relief under the Bankruptcy Code, or shall consent to the filing of a
bankruptcy proceeding against it, or shall file a petition or answer or consent
seeking reorganization or liquidation under the Bankruptcy Code or any other
similar applicable Federal or State law, or shall consent to the filing of any
such petition, or shall consent to the appointment of a receiver or liquidator
or trustee or assignee in bankruptcy or insolvency of it or of its property, or
shall make an assignment for the benefit of creditors, or shall admit in writing
its inability to pay its debts generally as they become due.

         "Threshold Appreciation Price" has the meaning specified in Section
5.1.

         "TIA" means the Trust Indenture Act of 1939, as amended, or any
successor statute.

         "Trading Day" has the meaning specified in Section 5.1.

                                       13
<PAGE>   19


         "Treasury Portfolio" means (1) in connection with the Initial
Remarketing, a portfolio of zero-coupon U.S. Treasury Securities consisting of
(a) principal or interest strips of U.S. Treasury Securities which mature on or
prior to ____________, 2004 in an aggregate amount equal to the Applicable
Principal Amount and (b) with respect to the scheduled interest payment date on
the Debentures that occurs on the Purchase Contract Settlement Date, principal
or interest strips of U.S. Treasury Securities which mature on or prior to such
date in an aggregate amount equal to the aggregate interest payment that would
be due on the Applicable Principal Amount of the Debentures on such date if the
applicable Coupon Rate on the Debentures were not reset to the Reset Rate as
described in Section 4.1 and (2) in connection with a Tax Event Redemption, (a)
if the Tax Event Redemption Date occurs prior to _________________, 2003 or, in
the event of a Failed Initial Remarketing, prior to the Purchase Contract
Settlement Date, a portfolio of zero-coupon U.S. Treasury Securities consisting
of (i) principal or interest strips of U.S. Treasury Securities which mature on
or prior to ____________, 2004 in an aggregate amount equal to the applicable
Tax Event Redemption Principal Amount and (ii) with respect to each scheduled
interest payment date on the Debentures that occurs after the Tax Event
Redemption Date and on or before the Purchase Contract Settlement Date,
principal or interest strips of U.S. Treasury Securities which mature on or
prior to such date in an aggregate amount equal to the aggregate interest
payment that would be due on the applicable Tax Event Redemption Principal
Amount of the Debentures on such date, and (b) if the Tax Event Redemption Date
occurs on or after ____________________, 2003 or, in the event of a Failed
Initial Remarketing, on or after the Purchase Contract Settlement Date, a
portfolio of zero-coupon U.S. Treasury Securities consisting of (i) principal or
interest strips of U.S. Treasury Securities which mature on or prior
to_________, 2006 in an aggregate amount equal to the applicable Tax Event
Redemption Principal Amount and (ii) with respect to each scheduled interest
payment date on the Debentures that occurs after the Tax Event Redemption Date,
principal or interest strips of such U.S. Treasury Securities which mature on or
prior to such date in an aggregate amount equal to the aggregate interest
payment that would be due on the applicable Tax Event Redemption Principal
Amount of the Debentures on such date.

         "Treasury Portfolio Purchase Price" means the lowest aggregate price
quoted by the Primary Treasury Dealer to the Quotation Agent (a) in the case of
a Tax Event Redemption, on the third Business Day immediately preceding the Tax
Event Redemption Date for the purchase of the applicable Treasury Portfolio for
settlement on the Tax Event Redemption Date and (b) in the case of the Initial
Remarketing, on the Initial Remarketing Date for the purchase of the applicable
Treasury Portfolio for settlement on ____________________, 2003.


                                       14
<PAGE>   20

         "Treasury Security" means zero-coupon U.S. Treasury Securities (CUSIP
Number ________) which are the principal strip of the U.S. Treasury Securities
which mature on ______________, 2004.

         "Treasury Units" means the collective rights and obligations of a
Holder of a Treasury Units Certificate in respect of the Treasury Securities,
subject to the Pledge thereof, and the related Purchase Contract.

         "Treasury Units Certificate" means a certificate evidencing the rights
and obligations of a Holder in respect of the number of Treasury Units specified
on such certificate.

         "Treasury Units Register" and "Treasury Units Registrar" have the
respective meanings specified in Section 3.5.

         "Two-Year Benchmark Treasury" means direct obligations of the United
States (which may be obligations traded on a when-issued basis only) having a
maturity comparable to the remaining term to maturity of the Debentures, as
agreed upon by the Sponsor and the Reset Agent. The rate for the Two-Year
Benchmark Treasury will be the bid side rate displayed at 10:00 A.M., New York
City time, on the third Business Day immediately preceding the Purchase Contract
Settlement Date in the Telerate system (or if the Telerate system is (a) no
longer available on the Secondary Remarketing Date or (b) in the opinion of the
Reset Agent (after consultation with the Company) no longer an appropriate
system from which to obtain such rate, such other nationally recognized
quotation system as, in the opinion of the Reset Agent (after consultation with
the Company) is appropriate). If such rate is not so displayed, the rate for the
Two-Year Benchmark Treasury shall be, as calculated by the Reset Agent, the
yield to maturity for the Two-Year Benchmark Treasury, expressed as a bond
equivalent on the basis of a year of 365 or 366 days, as applicable, and applied
on a daily basis, and computed by taking the arithmetic mean of the secondary
market bid rates, as of 10:30 A.M., New York City time, on the Secondary
Remarketing Date of three leading United States government securities dealers
selected by the Reset Agent (after consultation with the Company)(which may
include the Reset Agent or an Affiliate thereof).

         "Two and One-Quarter Year Benchmark Treasury" means direct obligations
of the United States (which may be obligations traded on a when-issued basis
only) having a maturity comparable to the remaining term to maturity of the
Debentures, as agreed upon by the Sponsor and the Reset Agent. The rate for the
Two and One-Quarter Year Benchmark Treasury will be the bid side rate displayed
at 10:00 A.M.,


                                       15
<PAGE>   21

New York City time, on the Initial Remarketing Date in the Telerate system (or
if the Telerate system is (a) no longer available on the Initial Remarketing
Date or (b) in the opinion of the Reset Agent (after consultation with the
Company) no longer an appropriate system from which to obtain such rate, such
other nationally recognized quotation system as, in the opinion of the Reset
Agent (after consultation with the Company) is appropriate). If such rate is not
so displayed, the rate for the Two and One-Quarter Year Benchmark Treasury shall
be, as calculated by the Reset Agent, the yield to maturity for the Two and
One-Quarter Year Benchmark Treasury, expressed as a bond equivalent on the basis
of a year of 365 or 366 days, as applicable, and applied on a daily basis, and
computed by taking the arithmetic mean of the secondary market bid rates, as of
10:30 A.M., New York City time, on the Initial Remarketing Date of three leading
United States government securities dealers selected by the Reset Agent (after
consultation with the Company) (which may include the Reset Agent or an
Affiliate thereof).

         "Underwriting Agreement" means the Underwriting Agreement dated
_________, 2001 among the Company, and Merrill Lynch, Pierce, Fenner & Smith
Incorporated, Credit Suisse First Boston Corporation, CIBC World Markets Corp.,
J.P. Morgan Securities Inc. and Salomon Smith Barney Inc., as representatives of
the underwriters named therein.

         "Vice President" means any vice president, whether or not designated by
a number or a word or words added before or after the title "vice president."

Section 1.2. Compliance Certificates and Opinions.

         Except as otherwise expressly provided by this Agreement, upon any
application or request by the Company to the Agent to take any action under any
provision of this Agreement, the Company shall furnish to the Agent an Officer's
Certificate stating that all conditions precedent, if any, provided for in this
Agreement relating to the proposed action have been complied with and, if
reasonably requested by the Agent, an Opinion of Counsel stating that, in the
opinion of such counsel, all such conditions precedent, if any, have been
complied with, except that in the case of any such application or request as to
which the furnishing of such documents is specifically required by any provision
of this Agreement relating to such particular application or request, no
additional certificate or opinion need be furnished.

         Every certificate or opinion with respect to compliance with a
condition or covenant provided for in this Agreement shall include:


                                       16
<PAGE>   22

                  (1) a statement that each Person signing such certificate or
         opinion has read such covenant or condition and the definitions herein
         relating thereto;

                  (2) a brief statement as to the nature and scope of the
         examination or investigation upon which the statements or opinions
         contained in such certificate or opinion are based;

                  (3) a statement that, in the opinion of each such Person, he
         or she or it has made such examination or investigation as is necessary
         to enable such individual to express an informed opinion as to whether
         or not such covenant or condition has been complied with; and

                  (4) a statement as to whether, in the opinion of each such
         Person, such condition or covenant has been complied with.

Section 1.3.      Form of Documents Delivered to Agent.

         In any case where several matters are required to be certified by, or
covered by an opinion of, any specified Person, it is not necessary that all
such matters be certified by, or covered by the opinion of, only one such
Person, or that they be so certified or covered by only one document, but one
such Person may certify or give an opinion with respect to some matters and one
or more other such Persons as to other matters, and any such Person may certify
or give an opinion as to such matters in one or several documents.

         Any certificate or opinion of the Company may be based, insofar as it
relates to legal matters, upon a certificate or opinion of, or representations
by, counsel, unless the Company knows, or in the exercise of reasonable care
should know, that the certificate or opinion or representations with respect to
the matters upon which his certificate or opinion is based are erroneous. Any
such certificate or Opinion of Counsel may be based, insofar as it relates to
factual matters, upon a certificate or opinion of, or representations by, the
Company stating that the information with respect to such factual matters is in
the possession of the Company unless the Person giving such certificate or
Opinion of Counsel knows, or in the exercise of reasonable care should know,
that the certificate or opinion or representations with respect to such matters
are erroneous.

         Where any Person is required to make, give or execute two or more
applications, requests, consents, certificates, statements, opinions or other


                                       17
<PAGE>   23

instruments under this Agreement, they may, but need not, be consolidated and
form one instrument.

Section 1.4. Acts of Holders; Record Dates.

         (a) Any request, demand, authorization, direction, notice, consent,
waiver or other action provided by this Agreement to be given or taken by
Holders may be embodied in and evidenced by one or more instruments of
substantially similar tenor signed by such Holders in person or by agent duly
appointed in writing; and, except as herein otherwise expressly provided, such
action shall become effective when such instrument or instruments are delivered
to the Agent and, where it is hereby expressly required, to the Company. Such
instrument or instruments (and the action embodied therein and evidenced
thereby) are herein sometimes referred to as the "Act" of the Holders signing
such instrument or instruments. Proof of execution of any such instrument or of
a writing appointing any such agent shall be sufficient for any purpose of this
Agreement and (subject to Section 7.1) conclusive in favor of the Agent and the
Company, if made in the manner provided in this Section.

         (b) The fact and date of the execution by any Person of any such
instrument or writing may be proved in any manner which the Agent deems
sufficient.

         (c) The ownership of Securities shall be proved by the Corporate Units
Register or the Treasury Units Register, as the case may be.

         (d) Any request, demand, authorization, direction, notice, consent,
waiver or other Act of the Holder of any Certificate shall bind every future
Holder of the same Certificate and the Holder of every Certificate issued upon
the registration of transfer thereof or in exchange therefor or in lieu thereof
in respect of anything done, omitted or suffered to be done by the Agent or the
Company in reliance thereon, whether or not notation of such action is made upon
such Certificate.

         (e) The Company may set any day as a record date for the purpose of
determining the Holders of Outstanding Securities entitled to give, make or take
any request, demand, authorization, direction, notice, consent, waiver or other
action provided or permitted by this Agreement to be given, made or taken by
Holders of Securities. If any record date is set pursuant to this paragraph, the
Holders of the Outstanding Corporate Units and the Outstanding Treasury Units,
as the case may be, on such record date, and no other Holders, shall be entitled
to take the relevant action with respect to the Corporate Units or the Treasury
Units, as the case may be,


                                       18
<PAGE>   24

whether or not such Holders remain Holders after such record date; provided that
no such action shall be effective hereunder unless taken on or prior to the
applicable Expiration Date by Holders of the requisite number of Outstanding
Securities on such record date. Nothing in this paragraph shall be construed to
prevent the Company from setting a new record date for any action for which a
record date has previously been set pursuant to this paragraph (whereupon the
record date previously set shall automatically and with no action by any Person
be cancelled and of no effect), and nothing in this paragraph shall be construed
to render ineffective any action taken by Holders of the requisite number of
Outstanding Securities on the date such action is taken. Promptly after any
record date is set pursuant to this paragraph, the Company, at its own expense,
shall cause notice of such record date, the proposed action by Holders and the
applicable Expiration Date to be given to the Agent in writing and to each
Holder of Securities in the manner set forth in Section 1.6.

         With respect to any record date set pursuant to this Section, the
Company may designate any date as the "Expiration Date" and from time to time
may change the Expiration Date to any earlier or later day; provided that no
such change shall be effective unless notice of the proposed new Expiration Date
is given to the Agent in writing, and to each Holder of Securities in the manner
set forth in Section 1.6, on or prior to the existing Expiration Date. If an
Expiration Date is not designated with respect to any record date set pursuant
to this Section, the Company shall be deemed to have initially designated the
180th day after such record date as the Expiration Date with respect thereto,
subject to its right to change the Expiration Date as provided in this
paragraph. Notwithstanding the foregoing, no Expiration Date shall be later than
the 180th day after the applicable record date.

Section 1.5.      Notices.

         Any request, demand, authorization, direction, notice, consent, waiver
or Act of Holders or other document provided or permitted by this Agreement to
be made upon, given or furnished to, or filed with,

                  (1) the Agent by any Holder or by the Company shall be
         sufficient for every purpose hereunder (unless otherwise herein
         expressly provided) if made, given, furnished or filed in writing and
         personally delivered or mailed, first-class postage prepaid, to the
         Agent at ___________________________, or at any other address
         previously furnished in writing by the Agent to the Holders and the
         Company; or


                                       19
<PAGE>   25

                  (2) the Company by the Agent or by any Holder shall be
         sufficient for every purpose hereunder (unless otherwise herein
         expressly provided) if made, given, furnished or filed in writing and
         personally delivered or mailed, first-class postage prepaid, to the
         Company at NRG Energy, Inc., 901 Marquette Avenue, Suite 2300,
         Minneapolis, MN 55402, Attention: Chief Financial Officer, or at any
         other address previously furnished in writing to the Agent by the
         Company; or

                  (3) the Collateral Agent by the Agent, the Company or any
         Holder shall be sufficient for every purpose hereunder (unless
         otherwise herein expressly provided) if made, given, furnished or filed
         in writing and personally delivered or mailed, first-class postage
         prepaid, addressed to the Collateral Agent at
         _________________________________________________, or at any other
         address previously furnished in writing by the Collateral Agent to the
         Agent, the Company and the Holders; or

                  (4) the Indenture Trustee by the Company shall be sufficient
         for every purpose hereunder (unless otherwise herein expressly
         provided) if made, given, furnished or filed in writing and personally
         delivered or mailed, first-class postage prepaid, addressed to the
         Indenture Trustee at __________________________, or at any other
         address previously furnished in writing by the Indenture Trustee to the
         Company.

Section 1.6.      Notice to Holders; Waiver.

         Where this Agreement provides for notice to Holders of any event, such
notice shall be sufficiently given (unless otherwise herein expressly provided)
if in writing and mailed, first-class postage prepaid, to each Holder affected
by such event, at its address as it appears in the applicable Register, not
later than the latest date, and not earlier than the earliest date, prescribed
for the giving of such notice. In any case where notice to Holders is given by
mail, neither the failure to mail such notice, nor any defect in any notice so
mailed, to any particular Holder shall affect the sufficiency of such notice
with respect to other Holders. Where this Agreement provides for notice in any
manner, such notice may be waived in writing by the Person entitled to receive
such notice, either before or after the event, and such waiver shall be the
equivalent of such notice. Waivers of notice by Holders shall be filed with the
Agent, but such filing shall not be a condition precedent to the validity of any
action taken in reliance upon such waiver.


                                       20
<PAGE>   26

         In case by reason of the suspension of regular mail service or by
reason of any other cause it shall be impracticable to give such notice by mail,
then such notification as shall be made with the approval of the Agent shall
constitute a sufficient notification for every purpose hereunder.

Section 1.7.      Effect of Headings and Table of Contents.

         The Article and Section headings herein and the Table of Contents are
for convenience only and shall not affect the construction hereof.

Section 1.8.      Successors and Assigns.

         All covenants and agreements in this Agreement by the Company shall
bind its successors and assigns, whether so expressed or not.

Section 1.9.      Separability Clause.

         In case any provision in this Agreement or in the Securities shall be
invalid, illegal or unenforceable, then, to the extent permitted by law, the
validity, legality and enforceability of the remaining provisions hereof and
thereof shall not in any way be affected or impaired thereby.

Section 1.10.     Benefits of Agreement.

         Nothing in this Agreement or in the Securities, express or implied,
shall give to any Person, other than the parties hereto and their successors
hereunder and, to the extent provided hereby, the Holders, any benefits or any
legal or equitable right, remedy or claim under this Agreement. The Holders from
time to time shall be beneficiaries of this Agreement and shall be bound by all
of the applicable terms and conditions hereof and of the Securities evidenced by
their Certificates by their acceptance of delivery of such Certificates.

Section 1.11.     Governing Law.

         THIS AGREEMENT AND THE SECURITIES SHALL BE GOVERNED BY AND CONSTRUED IN
ACCORDANCE WITH THE LAWS OF THE STATE OF NEW YORK, WITHOUT REGARD TO PRINCIPLES
OF CONFLICTS OF LAWS.


                                       21
<PAGE>   27

Section 1.12.     Legal Holidays.

         In any case where any Purchase Contract Settlement Date shall not be a
Business Day, then (notwithstanding any other provision of this Agreement, the
Corporate Units Certificates or the Treasury Units Certificates), the Purchase
Contracts shall not be performed on such date, but the Purchase Contracts shall
be performed on the immediately following Business Day with the same force and
effect as if performed on the Purchase Contract Settlement Date.

Section 1.13.     Counterparts.

         This Agreement may be executed in any number of counterparts by the
parties hereto on separate counterparts, each of which, when so executed and
delivered, shall be deemed an original, but all such counterparts shall together
constitute one and the same instrument.

Section 1.14.     Inspection of Agreement.

         A copy of this Agreement shall be available at all reasonable times
during normal business hours at the Corporate Trust Office for inspection by any
Holder.


                                   ARTICLE II

                                Certificate Forms

Section 2.1.      Forms of Certificates Generally.

         The Corporate Units Certificates (including the form of Purchase
Contract forming part of the Corporate Units evidenced thereby) shall be in
substantially the form set forth in Exhibit A hereto, with such letters, numbers
or other marks of identification or designation and such legends or endorsements
printed, lithographed or engraved thereon as may be required by the rules of any
securities exchange on which the Corporate Units are listed or any depositary
therefor, or as may, consistently herewith, be determined by the officers of the
Company executing such Corporate Units Certificates, as evidenced by their
execution of the Corporate Units Certificates.

         The definitive Corporate Units Certificates shall be printed,
lithographed or engraved on steel engraved borders or may be produced in any
other manner, all as

                                       22

<PAGE>   28


determined by the officers of the Company executing such Corporate Units
Certificates, consistent with the provisions of this Agreement, as evidenced by
their execution thereof.

         The Treasury Units Certificates (including the form of Purchase
Contract forming part of the Treasury Units evidenced thereby) shall be in
substantially the form set forth in Exhibit B hereto, with such letters, numbers
or other marks of identification or designation and such legends or endorsements
printed, lithographed or engraved thereon as may be required by the rules of any
securities exchange on which the Treasury Units are listed or any depositary
therefor, or as may, consistently herewith, be determined by the officers of
the Company executing such Treasury Units Certificates, as evidenced by their
execution of the Treasury Units Certificates.

         The definitive Treasury Units Certificates shall be printed,
lithographed or engraved on steel engraved borders or may be produced in any
other manner, all as determined by the officers of the Company executing such
Treasury Units Certificates, consistent with the provisions of this Agreement,
as evidenced by their execution thereof.

         Every Global Certificate authenticated, executed on behalf of the
Holders and delivered hereunder shall bear a legend in substantially the
following form:

         THIS CERTIFICATE IS A GLOBAL CERTIFICATE WITHIN THE MEANING OF THE
         PURCHASE CONTRACT AGREEMENT (AS HEREINAFTER DEFINED) AND IS REGISTERED
         IN THE NAME OF THE CLEARING AGENCY OR A NOMINEE THEREOF. THIS
         CERTIFICATE MAY NOT BE EXCHANGED IN WHOLE OR IN PART FOR A CERTIFICATE
         REGISTERED, AND NO TRANSFER OF THIS CERTIFICATE IN WHOLE OR IN PART
         MAY BE REGISTERED, IN THE NAME OF ANY PERSON OTHER THAN SUCH CLEARING
         AGENCY OR A NOMINEE THEREOF, EXCEPT IN THE LIMITED CIRCUMSTANCES
         DESCRIBED IN THE PURCHASE CONTRACT AGREEMENT.

Section 2.2.      Form of Agent's Certificate of Authentication.

         The form of the Agent's certificate of authentication of the Corporate
Units shall be in substantially the form set forth on the form of the Corporate
Units Certificates.


                                       23

<PAGE>   29

         The form of the Agent's certificate of authentication of the Treasury
Units shall be in substantially the form set forth on the form of the Treasury
Units Certificates.


                                   ARTICLE III

                                 The Securities

Section 3.1.      Title and Terms; Denominations.

         The aggregate number of Corporate Units and Treasury Units evidenced by
Certificates authenticated, executed on behalf of the Holders and delivered
hereunder is limited to $[200,000,000] (or $[230,000,000] if the Underwriters'
overallotment option is exercised in full) except for Certificates
authenticated, executed and delivered upon registration of transfer of, in
exchange for, or in lieu of, other Certificates pursuant to Section 3.4, 3.5,
3.9, 3.10, 3.13, 3.14, 5.9 or 8.5.

         The Certificates shall be issuable only in registered form and only in
denominations of a single Corporate Unit or Treasury Unit and any integral
multiple thereof.

Section 3.2.      Rights and Obligations Evidenced by the Certificates.

         Each Corporate Units Certificate shall evidence the number of Corporate
Units specified therein, with each such Corporate Unit representing the
ownership by the Holder thereof of a beneficial interest in a Debenture or the
Applicable Owner ship Interest of the Treasury Portfolio, as the case may be,
subject to the Pledge of such Debenture or the Applicable Ownership Interest of
the Treasury Portfolio, as the case may be, by such Holder pursuant to the
Pledge Agreement, and the rights and obligations of the Holder thereof and the
Company under one Purchase Contract. The Agent as attorney-in-fact for, and on
behalf of, the Holder of each Corporate Unit shall pledge, pursuant to the
Pledge Agreement, the Debenture or the Applicable Ownership Interest of the
Treasury Portfolio, as the case may be, forming a part of such Corporate Unit,
to the Collateral Agent and grant to the Collateral Agent a security interest in
the right, title, and interest of such Holder in such Debenture or the
Applicable Ownership Interest of the Treasury Portfolio, as the case may be, for
the benefit of the Company, to secure the obligation of the Holder under each
Purchase Contract to purchase the Common Stock of the Company.


                                       24

<PAGE>   30


         Each Treasury Units Certificate shall evidence the number of Treasury
Units specified therein, with each such Treasury Unit representing the ownership
by the Holder thereof of a 1/40, or 2.5%, undivided beneficial interest in a
Treasury Security with a principal amount at maturity equal to $1,000, subject
to the Pledge of such Treasury Security by such Holder pursuant to the Pledge
Agreement, and the rights and obligations of the Holder thereof and the Company
under one Purchase Contract. The Agent as attorney-in-fact for, and on behalf
of, the Holder of each Treasury Unit shall pledge, pursuant to the Pledge
Agreement, the Treasury Security to the Collateral Agent and grant to the
Collateral Agent a security interest in the right, title and interest of such
Holder in such Treasury Security, for the benefit of the Company, to secure the
obligation of the Holder under each Purchase Contract to purchase the Common
Stock of the Company.

Section 3.3.      Execution, Authentication, Delivery and Dating.

         Subject to the provisions of Sections 3.13 and 3.14 hereof, upon the
execution and delivery of this Agreement, and at any time and from time to time
thereafter, the Company may deliver Certificates executed by the Company to the
Agent for authentication, execution on behalf of the Holders and delivery,
together with its Issuer Order for authentication of such Certificates, and the
Agent in accordance with such Issuer Order shall authenticate, execute on behalf
of the Holders and deliver such Certificates.

         The Certificates shall be executed on behalf of the Company by its
Chairman of the Board, its President or one of its Vice Presidents and its
Treasurer or one of its Assistant Treasurers or its Secretary or one of its
Assistant Secretaries. The signature of any of these officers on the
Certificates may be manual or facsimile.

         Certificates bearing the manual or facsimile signatures of individuals
who were at any time the proper officers of the Company shall bind the Company,
notwithstanding that such individuals or any of them have ceased to hold such
offices prior to the authentication and delivery of such Certificates or did not
hold such offices at the date of such Certificates.

         No Purchase Contract evidenced by a Certificate shall be valid until
such Certificate has been executed on behalf of the Holder by the manual
signature of an authorized signatory of the Agent, as such Holder's
attorney-in-fact. Such signature by an authorized signatory of the Agent shall
be conclusive evidence that the Holder of such Certificate has entered into the
Purchase Contracts evidenced by such Certificate.


                                       25

<PAGE>   31




         Each Certificate shall be dated the date of its authentication.

         No Certificate shall be entitled to any benefit under this Agreement or
be valid or obligatory for any purpose unless there appears on such Certificate
a certificate of authentication substantially in the form provided for herein
executed by an authorized signatory of the Agent by manual signature, and such
certificate upon any Certificate shall be conclusive evidence, and the only
evidence, that such Certificate has been duly authenticated and delivered
hereunder.

Section 3.4.      Temporary Certificates.

         Pending the preparation of definitive Certificates, the Company shall
execute and deliver to the Agent, and the Agent shall authenticate, execute on
behalf of the Holders, and deliver, in lieu of such definitive Certificates,
temporary Certificates which are in substantially the form set forth in Exhibit
A or Exhibit B hereto, as the case may be, with such letters, numbers or other
marks of identification or designation and such legends or endorsements
printed, lithographed or engraved thereon as may be required by the rules of any
securities exchange on which the Corporate Units or Treasury Units are listed,
or as may, consistently herewith, be determined by the officers of the Company
executing such Certificates, as evidenced by their execution of the
Certificates.

         If temporary Certificates are issued, the Company will cause definitive
Certificates to be prepared without unreasonable delay. After the preparation of
definitive Certificates, the temporary Certificates shall be exchangeable for
definitive Certificates upon surrender of the temporary Certificates at the
Corporate Trust Office or the New York office, at the expense of the Company and
without charge to the Holder. Upon surrender for cancellation of any one or more
temporary Certificates, the Company shall execute and deliver to the Agent, and
the Agent shall authenticate, execute on behalf of the Holder, and deliver in
exchange therefor, one or more definitive Certificates of like tenor and
denominations and evidencing a like number of Corporate Units or Treasury Units,
as the case may be, as the temporary Certificate or Certificates so surrendered.
Until so exchanged, the temporary Certificates shall in all respects evidence
the same benefits and the same obligations with respect to the Corporate Units
or Treasury Units, as the case may be, evidenced thereby as definitive
Certificates.


                                       26

<PAGE>   32




Section 3.5.      Registration; Registration of Transfer and Exchange.

         The Agent shall keep at the Corporate Trust Office a Register (the
"Corporate Units Register") in which, subject to such reasonable regulations as
it may prescribe, the Agent shall provide for the registration of Corporate
Units Certificates and of transfers of Corporate Units Certificates (the Agent,
in such capacity, the "Corporate Units Registrar") and a Register (the "Treasury
Units Register") in which, subject to such reasonable regulations as it may
prescribe, the Agent shall provide for the registration of Treasury Units
Certificates and of transfers of Treasury Units Certificates (the Agent, in such
capacity, the "Treasury Units Registrar").

         Upon surrender for registration of transfer of any Certificate at the
Corporate Trust Office or the New York Office, the Company shall execute and
deliver to the Agent, and the Agent shall authenticate, execute on behalf of the
designated transferee or transferees, and deliver, in the name of the
designated transferee or transferees, one or more new Certificates of any
authorized denominations, like tenor, and evidencing a like number of Corporate
Units or Treasury Units, as the case may be.

         At the option of the Holder, Certificates may be exchanged for other
Certificates, of any authorized denominations and evidencing a like number of
Corporate Units or Treasury Units, as the case may be, upon surrender of the
Certificates to be exchanged at the Corporate Trust Office or the New York
Office. Whenever any Certificates are so surrendered for exchange, the Company
shall execute and deliver to the Agent, and the Agent shall authenticate,
execute on behalf of the Holder, and deliver the Certificates which the Holder
making the exchange is entitled to receive.

         All Certificates issued upon any registration of transfer or exchange
of a Certificate shall evidence the ownership of the same number of Corporate
Units or Treasury Units, as the case may be, and be entitled to the same
benefits and subject to the same obligations, under this Agreement as the
Corporate Units or Treasury Units, as the case may be, evidenced by the
Certificate surrendered upon such registration of transfer or exchange.

         Every Certificate presented or surrendered for registration of transfer
or for exchange shall (if so required by the Agent) be duly endorsed, or be
accompanied by a written instrument of transfer in form satisfactory to the
Company and the Agent duly executed, by the Holder thereof or its attorney duly
authorized in writing.



                                       27

<PAGE>   33




         No service charge shall be made for any registration of transfer or
exchange of a Certificate, but the Company and the Agent may require payment
from the Holder of a sum sufficient to cover any tax or other governmental
charge that may be imposed in connection with any registration of transfer or
exchange of Certificates, other than any exchanges pursuant to Sections 3.4,
3.6, 3.9 and 8.5 not involving any transfer.

         Notwithstanding the foregoing, the Company shall not be obligated to
execute and deliver to the Agent, and the Agent shall not be obligated to
authenticate, execute on behalf of the Holder and deliver, any Certificate
presented or surrendered for registration of transfer or for exchange on or
after the Business Day immediately preceding the earlier of the Purchase
Contract Settlement Date or the Termination Date. In lieu of delivery of a new
Certificate, upon satisfaction of the applicable conditions specified above in
this Section and receipt of appropriate registration or transfer instructions
from such Holder, the Agent shall (i) if the Purchase Contract Settlement Date
has occurred, deliver the shares of Common Stock issuable in respect of the
Purchase Contracts forming a part of the Securities evidenced by such
Certificate (together with any cash or other property to which the Holder is
entitled), or (ii) if a Termination Event shall have occurred prior to the
Purchase Contract Settlement Date, transfer the Debentures, the appropriate
Applicable Ownership Interest of the Treasury Portfolio or the Treasury
Securities, as the case may be, evidenced thereby, in each case subject to the
applicable conditions and in accordance with the applicable provisions of
Article Five hereof.

Section 3.6.      Book-Entry Interests.

         The Certificates, on original issuance, will be issued in the form of
one or more fully registered Global Certificates, to be delivered to the
Depositary by, or on behalf of, the Company. Such Global Certificate shall
initially be registered on the books and records of the Company in the name of
Cede & Co., the nominee of the Depositary, and no Beneficial Owner will receive
a definitive Certificate representing such Beneficial Owner's interest in such
Global Certificate, except as provided in Section 3.9. The Agent shall enter
into an agreement with the Depositary if so requested by the Company. Unless and
until definitive, fully registered Certificates have been issued to Beneficial
Owners pursuant to Section 3.9:

              (a) the provisions of this Section 3.6 shall be in full force and
effect;



                                       28

<PAGE>   34





              (b) the Company shall be entitled to deal with the Clearing Agency
for all purposes of this Agreement (including receiving approvals, votes or
consents hereunder) as the Holder of the Securities and the sole holder of the
Global Certificate(s) and shall have no obligation to the Beneficial Owners;

              (c) to the extent that the provisions of this Section 3.6 conflict
with any other provisions of this Agreement, the provisions of this Section 3.6
shall control; and

              (d) the rights of the Beneficial Owners shall be exercised only
through the Clearing Agency and shall be limited to those established by law and
agreements between such Beneficial Owners and the Clearing Agency and/or the
Clearing Agency Participants. The Clearing Agency will make book entry transfers
among Clearing Agency Participants.

Section 3.7.      Notices to Holders.

         Whenever a notice or other communication to the Holders is required to
be given under this Agreement, the Company or the Company's agent shall give
such notices and communications to the Holders and, with respect to any
Securities registered in the name of a Clearing Agency or the nominee of a
Clearing Agency, the Company or the Company's agent shall, except as set forth
herein, have no obligations to the Beneficial Owners.

Section 3.8.      Appointment of Successor Clearing Agency.

         If any Clearing Agency elects to discontinue its services as securities
depositary with respect to the Securities, the Company may, in its sole
discretion, appoint a successor Clearing Agency with respect to the Securities.

Section 3.9.      Definitive Certificates.

         If (i) a Clearing Agency elects to discontinue its services as
securities depositary with respect to the Securities and a successor Clearing
Agency is not appointed within 90 days after such discontinuance pursuant to
Section 3.8, (ii) the Company elects to terminate the book-entry system through
the Clearing Agency with respect to the Securities, or (iii) there shall have
occurred and be continuing a default by the Company in respect of its
obligations under one or more Purchase Contracts, or one or more Debentures,
then upon surrender of the Global Certificates representing the Book-Entry
Interests with respect to the Securities by the Clearing





                                       29

<PAGE>   35





Agency, accompanied by registration instructions, the Company shall cause
definitive Certificates to be delivered to Beneficial Owners in accordance with
the instructions of the Clearing Agency. The Company shall not be liable for any
delay in delivery of such instructions and may conclusively rely on and shall be
protected in relying on, such instructions.

Section 3.10.     Mutilated, Destroyed, Lost and Stolen Certificates.

         If any mutilated Certificate is surrendered to the Agent, the Company
shall execute and deliver to the Agent, and the Agent shall authenticate,
execute on behalf of the Holder, and deliver in exchange therefor, a new
Certificate at the cost of the Holder, evidencing the same number of Corporate
Units or Treasury Units, as the case may be, and bearing a Certificate number
not contemporaneously outstanding.

         If there shall be delivered to the Company and the Agent (i) evidence
to their satisfaction of the destruction, loss or theft of any Certificate, and
(ii) such security or indemnity at the cost of the Holder as may be required by
them to hold each of them and any agent of any of them harmless, then, in the
absence of notice to the Company or the Agent that such Certificate has been
acquired by a bona fide purchaser, the Company shall execute and deliver to the
Agent, and the Agent shall authenticate, execute on behalf of the Holder, and
deliver to the Holder, in lieu of any such destroyed, lost or stolen
Certificate, a new Certificate, evidencing the same number of Corporate Units or
Treasury Units, as the case may be, and bearing a Certificate number not
contemporaneously outstanding.

         Notwithstanding the foregoing, the Company shall not be obligated to
execute and deliver to the Agent, and the Agent shall not be obligated to
authenticate, execute on behalf of the Holder, and deliver to the Holder, a
Certificate on or after the Business Day immediately preceding the earlier of
the Purchase Contract Settlement Date or the Termination Date. In lieu of
delivery of a new Certificate, upon satisfaction of the applicable conditions
specified above in this Section and receipt of appropriate registration or
transfer instructions from such Holder, the Agent shall (i) if the Purchase
Contract Settlement Date has occurred, deliver the shares of Common Stock
issuable in respect of the Purchase Contracts forming a part of the Securities
evidenced by such Certificate (together with any cash or other property to which
the Holder is entitled), or (ii) if a Termination Event shall have occurred
prior to the Purchase Contract Settlement Date, transfer the Debentures, the
appropriate Applicable Ownership Interest of the Treasury Portfolio or the
Treasury Securities, as the case may be, evidenced thereby, in each case subject
to the



                                       30

<PAGE>   36





applicable conditions and in accordance with the applicable provisions of
Article Five hereof.

         Upon the issuance of any new Certificate under this Section, the
Company and the Agent may require the payment by the Holder of a sum sufficient
to cover any tax or other governmental charge that may be imposed in relation
thereto and any other expenses (including the reasonable fees and expenses of
the Agent) connected therewith.

         Every new Certificate issued pursuant to this Section in lieu of any
destroyed, lost or stolen Certificate shall constitute an original additional
contractual obligation of the Company and of the Holder in respect of the
Security evidenced thereby, whether or not the destroyed, lost or stolen
Certificate (and the Securities evidenced thereby) shall be at any time
enforceable by anyone, and shall be entitled to all the benefits and be subject
to all the obligations of this Agreement equally and proportionately with any
and all other Certificates delivered hereunder.

         The provisions of this Section are exclusive and shall preclude (to the
extent lawful) all other rights and remedies with respect to the replacement or
payment of mutilated, destroyed, lost or stolen Certificates.

Section 3.11.     Persons Deemed Owners.

         Prior to due presentment of a Certificate for registration of transfer,
the Company and the Agent, and any agent of the Company or the Agent, may treat
the Person in whose name such Certificate is registered as the owner of the
Corporate Units or Treasury Units evidenced thereby, for the purpose of
receiving interest on the Debentures or on the maturing quarterly interest
strips of the Treasury Portfolio, as applicable, performance of the Purchase
Contracts and for all other purposes whatsoever, whether or not any interest on
the Debentures shall be overdue and notwithstanding any notice to the contrary,
and neither the Company nor the Agent, nor any agent of the Company or the
Agent, shall be affected by notice to the contrary.

         Notwithstanding the foregoing, with respect to any Global Certificate,
nothing herein shall prevent the Company, the Agent or any agent of the Company
or the Agent, from giving effect to any written certification, proxy or other
authorization furnished by any Clearing Agency (or its nominee), as a Holder,
with respect to such Global Certificate or impair, as between such Clearing
Agency and owners of beneficial interests in such Global Certificate, the
operation of customary practices



                                       31
<PAGE>   37

governing the exercise of rights of such Clearing Agency (or its nominee) as
Holder of such Global Certificate.

Section 3.12.     Cancellation.

         All Certificates surrendered for delivery of shares of Common Stock on
or after the Purchase Contract Settlement Date, upon the transfer of Debentures,
the appropriate Applicable Ownership Interest of the Treasury Portfolio or
Treasury Securities, as the case may be, after the occurrence of a Termination
Event or pursuant to an Early Settlement, or upon the registration of a transfer
or exchange of a Security, or a Collateral Substitution or the re-establishment
of a Corporate Unit or Treasury Unit shall, if surrendered to any Person other
than the Agent, be delivered to the Agent and, if not already cancelled, shall
be promptly cancelled by it. The Company may at any time deliver to the Agent
for cancellation any Certificates previously authenticated, executed and
delivered hereunder which the Company may have acquired in any manner
whatsoever, and all Certificates so delivered shall, upon Issuer Order, be
promptly cancelled by the Agent. No Certificates shall be authenticated,
executed on behalf of the Holder and delivered in lieu of or in exchange for any
Certificates cancelled as provided in this Section, except as expressly
permitted by this Agreement. All cancelled Certificates held by the Agent shall
upon written request be returned to the Company.

         If the Company or any Affiliate of the Company shall acquire any
Certificate, such acquisition shall not operate as a cancellation of such
Certificate unless and until such Certificate is delivered to the Agent
cancelled or for cancellation.

Section 3.13.     Establishment of Treasury Units.

         A Holder may separate the Debentures or the appropriate Applicable
Owner ship Interest of the Treasury Portfolio, as applicable, from the related
Purchase Contracts in respect of a Corporate Unit by substituting for such
Debentures or the appropriate Applicable Ownership Interest of the Treasury
Portfolio, as the case may be, Treasury Securities in an aggregate principal
amount of such Debentures or the appropriate Applicable Ownership Interest (as
specified in clause (A) of the definition of such term) of the Treasury
Portfolio, as applicable (a "Collateral Substitution"), at any time from and
after the date of this Agreement and on or prior to the fifth Business Day
immediately preceding the Purchase Contract Settlement Date in the case of the
Debentures and on or prior to the second Business Day immediately preceding the
Purchase Contract Settlement Date in the case of the appropriate Applicable
Ownership Interest of the Treasury Portfolio, in each case by



                                       32
<PAGE>   38

(a) depositing with the Collateral Agent Treasury Securities having an aggregate
principal amount equal to the aggregate principal amount of the Debentures
comprising part of such Corporate Units or the appropriate Applicable Ownership
Interest (as specified in clause (A) of the definition of such term) of the
Treasury Portfolio comprising part of such Corporate Units, as the case may be,
and (b) transferring the related Corporate Units to the Agent accompanied by a
notice to the Agent, substantially in the form of Exhibit D hereto, stating that
the Holder has transferred the relevant amount of Treasury Securities to the
Collateral Agent and requesting that the Agent instruct the Collateral Agent to
release the Debentures or the appropriate Applicable Owner ship Interest of the
Treasury Portfolio, as the case may be, underlying such Corporate Units,
whereupon the Agent shall promptly give such instruction to the Collateral
Agent, substantially in the form of Exhibit C hereto. Upon receipt of the
Treasury Securities described in clause (a) above and the instruction described
in clause (b) above, in accordance with the terms of the Pledge Agreement, the
Collateral Agent will release to the Agent, on behalf of the Holder, Debentures
or the appropriate Applicable Ownership Interest of the Treasury Portfolio, as
the case may be, having the appropriate aggregate principal amount in the case
of such Debentures or the appropriate Applicable Ownership Interest of the
Treasury Portfolio, as the case may be, from the Pledge, free and clear of the
Company's security interest therein, and upon receipt thereof the Agent shall
promptly:

              (i)   cancel the related Corporate Units;

              (ii)  transfer the Debentures or the appropriate Applicable Owner
         ship Interest of the Treasury Portfolio, as the case may be, to the
         Holder; and

              (iii) authenticate, execute on behalf of such Holder and deliver a
         Treasury Units Certificate executed by the Company in accordance with
         Section 3.3 evidencing the same number of Purchase Contracts as were
         evidenced by the cancelled Corporate Units.

         Holders who elect to separate the Debentures or the appropriate
Applicable Ownership Interest of the Treasury Portfolio, as the case may be,
from the related Purchase Contract and to substitute Treasury Securities for
such Debentures or the appropriate Applicable Ownership Interest of the Treasury
Portfolio, as the case may be, shall be responsible for any fees or expenses
payable to the Collateral Agent for its services as Collateral Agent in respect
of the substitution, and the Company shall not be responsible for any such fees
or expenses.



                                       33
<PAGE>   39

         Holders may make Collateral Substitutions (i) only in integral
multiples of 40 Corporate Units if Debentures are being substituted for by
Treasury Securities, or (ii) only in integral multiples of ___ Corporate Units
if the appropriate Applicable Ownership Interests of the Treasury Portfolio are
being substituted for by Treasury Securities.

         In the event a Holder making a Collateral Substitution pursuant to this
Section 3.13 fails to effect a book-entry transfer of the Corporate Units or
fails to deliver a Corporate Units Certificate(s) to the Agent after depositing
Treasury Securities with the Collateral Agent, the Debentures or the appropriate
Applicable Ownership Interest of the Treasury Portfolio, as the case may be,
constituting a part of such Corporate Units, and any interest on such Debenture
or the Applicable Ownership Interest of the Treasury Portfolio, as the case may
be, shall be held in the name of the Agent or its nominee in trust for the
benefit of such Holder, until such Corporate Units are so transferred or the
Corporate Units Certificate is so delivered, as the case may be, or, with
respect to a Corporate Units Certificate, such Holder provides evidence
satisfactory to the Company and the Agent that such Corporate Units Certificate
has been destroyed, lost or stolen, together with any indemnity that may be
required by the Agent and the Company.

         Except as described in this Section 3.13, for so long as the Purchase
Contract underlying a Corporate Unit remains in effect, such Corporate Unit
shall not be separable into its constituent parts, and the rights and
obligations of the Holder in respect of the Debentures or the appropriate
Applicable Ownership Interest of the Treasury Portfolio, as the case may be, and
Purchase Contract comprising such Corporate Unit may be acquired, and may be
transferred and exchanged, only as a Corporate Unit.

Section 3.14.     Reestablishment of Corporate Units.

         A Holder of a Treasury Unit may recreate Corporate Units at any time
(i) on or prior to the fifth Business Day immediately preceding the Purchase
Contract Settlement Date, if a Tax Event Redemption or a Successful Initial
Remarketing has not occurred, and (ii) on or prior to the second Business Day
immediately preceding the Purchase Contract Settlement Date, if a Tax Event
Redemption or a Successful Initial Remarketing has occurred and an Applicable
Ownership Interest in the Treasury Portfolio has become a component of the
Corporate Units, in each case by (a) depositing with the Collateral Agent
Debentures or the appropriate Applicable Ownership Interest of the Treasury
Portfolio, as the case may be, having an aggregate principal amount in the case
of the Debentures, or an appropriate Applicable





                                       34
<PAGE>   40

Ownership Interest (as defined in clause (A) of the definition of such term) of
the Treasury Portfolio, as the case may be, equal to the aggregate principal
amount of the Treasury Securities comprising part of the Treasury Units and (b)
transferring the related Treasury Units to the Agent accompanied by a notice to
the Agent, substantially in the form of Exhibit D hereto, stating that the
Holder has transferred the relevant amount of Debentures or the appropriate
Applicable Ownership Interest of the Treasury Portfolio, as the case may be, to
the Collateral Agent and requesting that the Agent instruct the Collateral Agent
to release the Treasury Securities underlying such Treasury Units, whereupon the
Agent shall promptly give such instruction to the Collateral Agent,
substantially in the form of Exhibit C hereto. Upon receipt of the Debentures or
the appropriate Applicable Ownership Interest of the Treasury Portfolio, as the
case may be, described in clause (a) above and the instruction described in
clause (b) above, in accordance with the terms of the Pledge Agreement, the
Collateral Agent will release to the Agent, on behalf of the Holder, the
Treasury Securities having a corresponding aggregate principal amount from the
Pledge, free and clear of the Company's security interest therein, and upon
receipt thereof the Agent shall promptly:

              (i)   cancel the related Treasury Units;

              (ii)  transfer the Treasury Securities to the Holder; and

              (iii) authenticate, execute on behalf of such Holder and deliver a
         Corporate Units Certificate executed by the Company in accordance with
         Section 3.3 evidencing the same number of Purchase Contracts as were
         evidenced by the cancelled Treasury Units.

         Holders of Treasury Units may reestablish Corporate Units in integral
multiples of 40 Treasury Units for 40 Corporate Units if a Tax Event Redemption
or a Successful Initial Remarketing has not occurred, and in integral multiples
of ____ Treasury Units for ___ Corporate Units if a Tax Event Redemption or a
Successful Initial Remarketing has occurred.

         In the event a Holder re-establishing Corporate Units pursuant to this
Section 3.14 fails to effect a book-entry transfer of the Treasury Units or
fails to deliver a Treasury Units Certificate(s) to the Agent after depositing
Debentures or the appropriate Applicable Ownership Interest of the Treasury
Portfolio, as the case may be, with the Collateral Agent, the Treasury
Securities constituting a part of such Treasury Units shall be held in the name
of the Agent or its nominee in trust for the benefit of such Holder, until such
Treasury Units are so transferred or the Treasury



                                       35
<PAGE>   41

Units Certificate is so delivered, as the case may be, or, with respect to a
Treasury Units Certificate, such Holder provides evidence satisfactory to the
Company and the Agent that such Treasury Units Certificate has been destroyed,
lost or stolen, together with any indemnity that may be required by the Agent
and the Company.

         Except as provided in this Section 3.14, for so long as the Purchase
Contract underlying a Treasury Unit remains in effect, such Treasury Unit shall
not be separable into its constituent parts and the rights and obligations of
the Holder of such Treasury Unit in respect of the Treasury Security and
Purchase Contract comprising such Treasury Unit may be acquired, and may be
transferred and ex changed, only as a Treasury Unit.

Section 3.15.     Transfer of Collateral upon Occurrence of Termination Event.

         Upon the occurrence of a Termination Event and the transfer to the
Agent of the Debentures, the appropriate Applicable Ownership Interest of the
Treasury Portfolio or the Treasury Securities, as the case may be, underlying
the Corporate Units and the Treasury Units pursuant to the terms of the Pledge
Agreement, the Agent shall request transfer instructions with respect to such
Debentures or the appropriate Applicable Ownership Interest of the Treasury
Portfolio or Treasury Securities, as the case may be, from each Holder by
written request mailed to such Holder at its address as it appears in the
Corporate Units Register or the Treasury Units Register, as the case may be.
Upon book-entry transfer of the Corporate Units or Treasury Units or delivery of
a Corporate Units Certificate or Treasury Units Certificate to the Agent with
such transfer instructions, the Agent shall transfer the Debentures, the
Applicable Ownership Interest of the Treasury Portfolio or Treasury Securities,
as the case may be, underlying such Corporate Units or Treasury Units, as the
case may be, to such Holder by book-entry transfer, or other appropriate
procedures, in accordance with such instructions; provided, however, that, to
the extent that a Holder of Corporate Units or Treasury Units would otherwise be
entitled to receive less than $1,000 principal amount at maturity of the
Treasury Portfolio or the Treasury Securities, the Agent shall dispose of such
securities for cash, and transfer the appropriate amount of such cash to such
Holder in accordance with such Holder's instructions. In the event a Holder of
Corporate Units or Treasury Units fails to effect such transfer or delivery, the
Debentures, the appropriate Applicable Owner ship Interest of the Treasury
Portfolio or Treasury Securities, as the case may be, underlying such Corporate
Units or Treasury Units, as the case may be, and any distributions thereon,
shall be held in the name of the Agent or its nominee in trust for the benefit
of such Holder, until such Corporate Units or Treasury Units are transferred or
the Corporate Units Certificate or Treasury Units Certificate is




                                       36
<PAGE>   42

surrendered or such Holder provides satisfactory evidence that such Corporate
Units Certificate or Treasury Units Certificate has been destroyed, lost or
stolen, together with any indemnity that may be required by the Agent and the
Company.

Section 3.16.     No Consent to Assumption.

         Each Holder of a Security, by acceptance thereof, shall be deemed
expressly to have withheld any consent to the assumption under Section 365 of
the Bankruptcy Code or otherwise, of the Purchase Contract by the Company,
receiver, liquidator or a person or entity performing similar functions, its
trustee in the event that the Company becomes the debtor under the Bankruptcy
Code or subject to other similar state or federal law providing for
reorganization or liquidation.

Section 3.17.     CUSIP Numbers

         The Company in issuing the Securities may use "CUSIP" numbers (if then
generally in use), and, if so, the Agent shall use "CUSIP" numbers in notices of
redemption as a convenience to Holders; provided that any such notice may state
that no representation is made as to the correctness of such numbers either as
printed on the Securities or as contained in any notice of a redemption and that
reliance may be placed only on the other identification numbers printed on the
Securities, and any such redemption shall not be affected by any defect in or
omission of such numbers. The Company will promptly notify the Agent of any
changes in the "CUSIP" numbers.

                                   ARTICLE IV

                                 The Debentures

Section 4.1.      Payment of Distribution; Rights to Distributions Preserved;
                  Distribution Rate Reset; Notice.

         A distribution on any Debenture or on the appropriate Applicable
Ownership Interest in the Treasury Portfolio, as the case may be, which is paid
on any Payment Date shall, subject to receipt thereof by the Agent from the
Collateral Agent as provided by the terms of the Pledge Agreement, be paid to
the Person in whose name the Corporate Units Certificate (or one or more
Predecessor Corporate Units Certificates) of which such Debenture or the
appropriate Applicable Ownership Interest of the Treasury Portfolio, as the case
may be, is a part is registered at the close of business on the Record Date for
such Payment Date.



                                       37
<PAGE>   43

         Each Corporate Units Certificate evidencing Debentures delivered under
this Agreement upon registration of transfer of or in exchange for or in lieu of
any other Corporate Units Certificate shall carry the rights to distributions
accrued and unpaid, and distributions to accrue, which were or will be carried
by the Debentures underlying such other Corporate Units Certificate.

         In the case of any Corporate Units with respect to which Cash
Settlement of the underlying Purchase Contract is effected on the Business Day
immediately preceding the Purchase Contract Settlement Date pursuant to prior
notice, or with respect to which Early Settlement of the underlying Purchase
Contract is effected on an Early Settlement Date, or with respect to which a
Collateral Substitution is effected, in each case on a date that is after any
Record Date and on or prior to the next succeeding Payment Date, interest on the
Debentures or distributions on the appropriate Applicable Ownership Interest of
the Treasury Portfolio, as the case may be, underlying such Corporate Units
otherwise payable on such Payment Date shall be payable on such Payment Date
notwithstanding such Cash Settlement or Early Settlement or Collateral
Substitution, and such distributions shall, subject to receipt thereof by the
Agent, be payable to the Person in whose name the Corporate Units Certificate
(or one or more Predecessor Certificates) was registered at the close of
business on the Record Date. Except as otherwise expressly provided in the
immediately preceding sentence, in the case of any Corporate Units with respect
to which Cash Settlement or Early Settlement of the underlying Purchase Contract
is effected on the Business Day immediately preceding the Purchase Contract
Settlement Date or an Early Settlement Date, as the case may be, or with respect
to which a Collateral Substitution has been effected, distributions on the
related Debentures or on the appropriate Applicable Ownership Interest of the
Treasury Portfolio, as the case may be, that would otherwise be payable after
the Purchase Contract Settlement Date or Early Settlement Date shall not be
payable hereunder to the Holder of such Corporate Units; provided, however, that
to the extent that such Holder continues to hold the separated Debentures that
formerly comprised a part of such Holder's Corporate Units, such Holder shall be
entitled to receive the distributions on such separated Debentures.

         The applicable Coupon Rate on the Debentures on and after ____, 2003
will be reset on the Initial Remarketing Date to the applicable Reset Rate (such
Reset Rate to be in effect on and after ____________________, 2003), except in
the event of a Failed Initial Remarketing. In the event of a Failed Initial
Remarketing, the applicable Coupon Rate on the Debentures outstanding on and
after the Purchase Contract Settlement Date will be reset on the Secondary
Remarketing Date to the applicable Reset Rate (such Reset Rate to be in effect
on and after the Purchase






                                       38
<PAGE>   44

Contract Settlement Date). On the applicable Reset Announcement Date the Reset
Spread and the Two-Year Benchmark Treasury or Two and One-Quarter Benchmark
Treasury, as applicable, to be used to determine the Reset Rate will be
announced by the Company. On the Business Day immediately following the Reset
Announcement Date, the Debentures Holders will be notified of such Reset Spread
and Two-Year Benchmark Treasury or Two and One-Quarter Benchmark Treasury, as
applicable, by the Company. Such notice shall be sufficiently given to Holders
of Debentures if published in an Authorized Newspaper in The City of New York.

         Not later than 7 calendar days nor more than 15 calendar days prior to
the Reset Announcement Date, the Company will notify the DTC or its nominee (or
any successor Clearing Agency or its nominee) by first-class mail, postage
prepaid, to notify the Beneficial Owners or Clearing Agency Participants holding
Corporate Units or Treasury Units of such Reset Announcement Date and, in the
case of a Secondary Remarketing, the procedures to be followed by Holders of
Corporate Units who intend to settle their obligation under the Purchase
Contract with separate cash on the Purchase Contract Settlement Date.

Section 4.2.      Notice and Voting.

         Under the terms of the Pledge Agreement, the Agent will be entitled to
exercise the voting and any other consensual rights pertaining to the Debentures
pledged with the Collateral Agent but only to the extent instructed by the
Holders as described below. Upon receipt of notice of any meeting at which
holders of Debentures are entitled to vote or upon any solicitation of consents,
waivers or proxies of holders of Debentures, the Agent shall, as soon as
practicable thereafter, mail to the Holders of Corporate Units a notice (a)
containing such information as is contained in the notice or solicitation, (b)
stating that each Holder on the record date set by the Agent therefor (which, to
the extent possible, shall be the same date as the record date for determining
the holders of Debentures entitled to vote) shall be entitled to instruct the
Agent as to the exercise of the voting rights pertaining to the Debentures
underlying their Corporate Units and (c) stating the manner in which such
instructions may be given. Upon the written request of the Holders of Corporate
Units on such record date, the Agent shall endeavor insofar as practicable to
vote or cause to be voted, in accordance with the instructions set forth in such
requests, the maximum number of Debentures as to which any particular voting
instructions are received. In the absence of specific instructions from the
Holder of a Corporate Unit, the Agent shall abstain from voting the Debentures
underlying such Corporate Units. The Company hereby agrees, if applicable, to
solicit Holders of




                                       39
<PAGE>   45

Corporate Units to timely instruct the Agent in order to enable the Agent to
vote such Debentures.

Section 4.3.      Tax Event Redemption.

         Upon the occurrence of a Tax Event Redemption prior to
____________________, 2003, or in the event of a Failed Initial Remarketing,
prior to the Purchase Contract Settlement Date, pursuant to the terms of the
Pledge Agreement, the Collateral Agent will apply, out of the aggregate
Redemption Price for the Debentures that are components of Corporate Units, an
amount equal to the aggregate Redemption Amount for the Debentures that are
components of Corporate Units to purchase on behalf of the Holders of Corporate
Units the Treasury Portfolio and promptly remit the remaining portion of such
Redemption Price to the Agent for payment to the Holders of such Corporate
Units. The Treasury Portfolio will be substituted for the pledged Debentures,
and will be held by the Collateral Agent in accordance with the terms of the
Pledge Agreement to secure the obligation of each Holder of a Corporate Unit to
purchase the Common Stock of the Company under the Purchase Contract
constituting a part of such Corporate Units. Following the occurrence of a Tax
Event Redemption prior to __________, 2003, or, in the event of a Failed Initial
Remarketing, prior to the Purchase Contract Settlement Date, the Holders of
Corporate Units and the Collateral Agent shall have such security interests,
rights and obligations with respect to the Treasury Portfolio as the Holder of
Corporate Units and the Collateral Agent had in respect of the Debentures, as
the case may be, subject to the Pledge thereof as provided in Sections 2, 3, 4,
5 and 6 of the Pledge Agreement, and any reference herein or in the Certificates
to the Debenture shall be deemed to be a reference to such Treasury Portfolio
and any reference herein or in the Certificates to interest on the Debentures
shall be deemed to be a reference to corresponding distributions on the Treasury
Portfolio. The Company may cause to be made in any Corporate Units Certificates
thereafter to be issued such change in phraseology and form (but not in
substance) as may be appropriate to reflect the substitution of the Treasury
Portfolio for Debentures as collateral.

Section 4.4.      CUSIP Numbers

         The Company in issuing the Debentures may use "CUSIP" numbers (if then
generally in use), and, if so, the Indenture Trustee shall use "CUSIP" numbers
in notices of redemption as a convenience to Holders; provided that any such
notice may state that no representation is made as to the correctness of such
numbers either as printed on the Debentures or as contained in any notice of a
redemption and that



                                       40
<PAGE>   46

reliance may be placed only on the other identification numbers printed on the
Debentures, and any such redemption shall not be affected by any defect in or
omission of such numbers. The Company will promptly notify the Indenture Trustee
and the Agent of any changes in the "CUSIP" numbers.


                                    ARTICLE V

                             The Purchase Contracts

Section 5.1.      Purchase of Shares of Common Stock.

         Each Purchase Contract shall, unless an Early Settlement has occurred
in accordance with Section 5.9 hereof, obligate the Holder of the related
Security to purchase, and the Company to sell, on the Purchase Contract
Settlement Date at a price equal to the Stated Amount (the "Purchase Price"), a
number of newly issued shares of Common Stock equal to the Settlement Rate
unless, on or prior to the Purchase Contract Settlement Date, there shall have
occurred a Termination Event with respect to the Security of which such Purchase
Contract is a part. The "Settlement Rate" is equal to (a) if the Applicable
Market Value (as defined below) is equal to or greater than $_____ (the
"Threshold Appreciation Price"), _____ shares of Common Stock per Purchase
Contract, (b) if the Applicable Market Value is less than the Threshold
Appreciation Price but is greater than $______, the number of shares of Common
Stock per Purchase Contract equal to the Stated Amount divided by the Applicable
Market Value and (c) if the Applicable Market Value is less than or equal to
$_______, _______ shares of Common Stock per Purchase Contract, in each case
subject to adjustment as provided in Section 5.6 (and in each case rounded
upward or downward to the nearest 1/10,000th of a share). As provided in Section
5.10, no fractional shares of Common Stock will be issued upon settlement of
Purchase Contracts.

         The "Applicable Market Value" means the average of the Closing Price
per share of Common Stock on each of the 20 consecutive Trading Days ending on
the third Trading Day immediately preceding the Purchase Contract Settlement
Date or, for purposes of determining cash payable in lieu of fractional shares
in connection with an Early Settlement, the third Trading Day immediately
preceding the relevant Early Settlement Date. The "Closing Price" of the Common
Stock on any date of determination means the closing sale price (or, if no
closing price is reported, the last reported sale price) of the Common Stock on
The New York Stock Exchange, Inc. (the "NYSE") on such date or, if the Common
Stock is not listed for trading on the



                                       41
<PAGE>   47

NYSE on any such date, as reported in the composite transactions for the
principal United States securities exchange on which the Common Stock is so
listed, or if the Common Stock is not so listed on a United States national or
regional securities exchange, as reported by the Nasdaq National Market or, if
the Common Stock is not so reported, the last quoted bid price for the Common
Stock in the over-the-counter market as reported by the National Quotation
Bureau or similar organization, or, if such bid price is not available, the
market value of the Common Stock on such date as determined by a nationally
recognized independent investment banking firm retained for this purpose by the
Company. A "Trading Day" means a day on which the Common Stock (A) is not
suspended from trading on any national or regional securities exchange or
association or over-the-counter market at the close of business and (B) has
traded at least once on the national or regional securities exchange or
association or over-the-counter market that is the primary market for the
trading of the Common Stock.

         Each Holder of a Corporate Unit or a Treasury Unit, by its acceptance
thereof, irrevocably authorizes the Agent to enter into and perform the related
Purchase Contract on its behalf as its attorney-in-fact (including the execution
of Certificates on behalf of such Holder), agrees to be bound by the terms and
provisions thereof, covenants and agrees to perform its obligations under such
Purchase Contracts, and consents to the provisions hereof, irrevocably
authorizes the Agent as its attorney-in-fact to enter into and perform the
Pledge Agreement on its behalf as its attorney-in-fact, and consents to and
agrees to be bound by the Pledge of the Debentures, the Treasury Portfolio or
the Treasury Securities pursuant to the Pledge Agreement; provided that upon a
Termination Event, the rights of the Holder of such Security under the Purchase
Contract may be enforced without regard to any other rights or obligations. Each
Holder of a Corporate Unit or Treasury Unit, by its acceptance thereof, further
covenants and agrees, that, to the extent and in the manner provided in Section
5.4 and the Pledge Agreement, but subject to the terms thereof, Proceeds of the
Treasury Securities, the Debentures or the Treasury Portfolio, as applicable,
on the Purchase Contract Settlement Date shall be paid by the Collateral Agent
to the Company in satisfaction of such Holder's obligations under such Purchase
Contract and such Holder shall acquire no right, title or interest in such
Proceeds.

         Upon registration of transfer of a Certificate, the transferee shall be
bound (without the necessity of any other action on the part of such
transferee), under the terms of this Agreement, the Purchase Contracts
underlying such Certificate and the Pledge Agreement and the transferor shall be
released from the obligations under this Agreement, the Purchase Contracts
underlying the Certificates so transferred and the



                                       42
<PAGE>   48

Pledge Agreement. The Company covenants and agrees, and each Holder of a
Certificate, by its acceptance thereof, likewise covenants and agrees, to be
bound by the provisions of this paragraph.

Section 5.2.      [Reserved]

Section 5.3.      Initial Remarketing.

         Unless a Tax Event Redemption has occurred, the Company shall engage a
nationally recognized investment bank (the "Remarketing Agent") pursuant to the
Remarketing Agreement to sell the Debentures of Corporate Unit Holders (the
"Initial Remarketing") on the third Business Day immediately preceding
_______________, 2003 (the "Initial Remarketing Date"). In order to facilitate
the remarketing, the Agent shall notify, by 10:00 a.m., New York City time, on
the Business Day immediately preceding the Initial Remarketing Date, the
Remarketing Agent of the aggregate principal amount of Debentures to be
remarketed. Concurrently, the Collateral Agent, pursuant to the terms of the
Pledge Agreement, will present for remarketing such Debentures to the
Remarketing Agent. Upon receipt of such notice from the Agent and such
Debentures from the Collateral Agent, the Remarketing Agent will, on the Initial
Remarketing Date, use its reasonable efforts to remarket such Debentures on such
date at a price of approximately 100.5% (but not less than 100%) of the Treasury
Portfolio Purchase Price. If the Remarketing Agent is able to remarket the
Debentures at a price equal to or greater than 100% of the Treasury Portfolio
Purchase Price (a "Successful Initial Remarketing"), the portion of the proceeds
from such Successful Initial Remarketing equal to the Treasury Portfolio
Purchase Price will be applied to purchase the Treasury Portfolio. In addition,
the Remarketing Agent may deduct as a remarketing fee ("Remarketing Fee") an
amount not exceeding 25 basis points (0.25%) of the Treasury Portfolio Purchase
Price from any amount of such proceeds in excess of the Treasury Portfolio
Purchase Price. Any proceeds in excess of those required to pay the Treasury
Portfolio Purchase Price and the Remarketing Fee will be remitted to the Agent
for payment to the Holders of the related Corporate Units. Corporate Units
Holders whose Debentures are so remarketed will not otherwise be responsible for
the payment of any Remarketing Fee in connection therewith. The Treasury
Portfolio will be substituted for the Debentures of Corporate Unit Holders and
will be pledged to the Collateral Agent to secure the Corporate Unit Holders'
obligation to pay the Purchase Price for the Common Stock under the related
Purchase Contracts on the Purchase Contract Settlement Date. Following the
occurrence of a Successful Initial Remarketing, the Holders of Corporate Units
and the Collateral Agent shall have such security interests, rights and
obligations with



                                       43
<PAGE>   49


respect to the Treasury Portfolio as the Holder of Corporate Units and the
Collateral Agent had in respect of the Debentures, as the case may be, subject
to the Pledge thereof as provided in Sections 2, 3, 4, 5 and 6 of the Pledge
Agreement, and any reference herein or in the Certificates to the Debenture
shall be deemed to be a reference to such Treasury Portfolio and any reference
herein or in the Certificates to interest on the Debentures shall be deemed to
be a reference to corresponding distributions on the Treasury Portfolio. The
Company may cause to be made in any Corporate Units Certificates thereafter to
be issued such change in phraseology and form (but not in substance) as may be
appropriate to reflect the substitution of the Treasury Portfolio for Debentures
as collateral.

         If, in spite of using its reasonable efforts, the Remarketing Agent
cannot remarket the related Debentures (other than to the Company) of such
Holders of Corporate Units at a price not less than 100% of the Treasury
Portfolio Purchase Price, the remarketing will be deemed to have failed (a
"Failed Initial Remarketing"). The Company will cause a notice of a Failed
Initial Remarketing to be published on the second Business Day immediately
preceding ___________, 2003 in a daily newspaper in the English language of
general circulation in The City of New York, which is expected to be The Wall
Street Journal.

Section 5.4.      Payment of Purchase Price.

                  (a) (i) Unless a Tax Event Redemption, Successful Initial
         Remarketing, Termination Event or Early Settlement has occurred, each
         Holder of a Corporate Unit may pay in cash ("Cash Settlement") the
         Purchase Price for the shares of Common Stock to be purchased pursuant
         to a Purchase Contract if such Holder notifies the Agent by use of a
         notice in substantially the form of Exhibit E hereto of its intention
         to make a Cash Settlement. Such notice shall be made on or prior to
         5:00 p.m., New York City time, on the fifth Business Day immediately
         preceding the Purchase Contract Settlement Date. The Agent shall
         promptly notify the Collateral Agent of the receipt of such a notice
         from a Holder intending to make a Cash Settlement.

                  (ii) A Holder of a Corporate Unit who has so notified the
         Agent of its intention to make a Cash Settlement is required to pay the
         Purchase Price to the Collateral Agent prior to 11:00 a.m., New York
         City time, on the Business Day immediately preceding the Purchase
         Contract Settlement Date in lawful money of the United States by
         certified or cashiers' check or wire transfer, in each case in
         immediately available funds payable to or upon the order of the
         Company. Any cash received by the Collateral Agent will be




                                       44
<PAGE>   50


         invested promptly by the Collateral Agent in Permitted Investments and
         paid to the Company on the Purchase Contract Settlement Date in
         settlement of the Purchase Contract in accordance with the terms of
         this Agreement and the Pledge Agreement. Any funds received by the
         Collateral Agent in respect of the investment earnings from the
         investment in such Permitted Investments, will be distributed to the
         Agent when received for payment to the Holder.

                   (iii) If a Holder of a Corporate Unit fails to notify the
         Agent of its intention to make a Cash Settlement in accordance with
         paragraph (a)(i) above, such failure shall constitute an event of
         default and the Holder shall be deemed to have consented to the
         disposition of the pledged Debentures pursuant to the Secondary
         Remarketing as described in paragraph (b) below. If a Holder of a
         Corporate Unit does notify the Agent as provided in paragraph (a)(i)
         above of its intention to pay the Purchase Price in cash, but fails to
         make such payment as required by paragraph (a)(ii) above, such failure
         shall also constitute a default; however, the Debentures of such a
         Holder will not be remarketed but instead the Collateral Agent, for the
         benefit of the Company, will exercise its rights as a secured party
         with respect to such Debentures, including but not limited to those
         rights specified in paragraph (c) below.

                   (b) Unless a Tax Event Redemption or a Successful Initial
         Remarketing has occurred, the Debentures of Corporate Unit Holders who
         have not notified the Agent of their intention to effect a Cash
         Settlement as provided in paragraph (a)(i) above will be sold by the
         Remarketing Agent (the "Secondary Remarketing") on the third Business
         Day immediately preceding the Purchase Contract Settlement Date (the
         "Secondary Remarketing Date"). The Agent shall notify, by 10:00 a.m.,
         New York City time, on the Business Day immediately preceding the
         Secondary Remarketing Date, the Remarketing Agent of the aggregate
         principal amount of Debentures to be remarketed. Concurrently, the
         Collateral Agent, pursuant to the terms of the Pledge Agreement, will
         present for remarketing such Debentures to the Remarketing Agent. Upon
         receipt of such notice from the Agent and such Debentures from the
         Collateral Agent, the Remarketing Agent will, on the Secondary
         Remarketing Date, use its reasonable efforts to remarket such
         Debentures on such date at a price of approximately 100.5% (but not
         less than 100%) of the aggregate principal amount of such Debentures.
         If the Remarketing Agent is able to remarket the Debentures at a price
         equal to or greater than 100% of the aggregate principal amount of
         Debentures (a "Successful Secondary Remarketing"), the Remarketing
         Agent





                                       45
<PAGE>   51


         will remit the entire amount of the proceeds from such Successful
         Secondary Remarketing to the Collateral Agent; provided, however, that
         the Remarketing Agent may deduct as the Remarketing Fee an amount not
         exceeding 25 basis points (0.25%) of the aggregate principal amount of
         the remarketed Debentures from any amount of the proceeds of a
         Successful Secondary Remarketing in excess of the aggregate principal
         amount of the remarketed Debentures. The portion of the proceeds equal
         to the aggregate principal amount of Debentures will automatically be
         applied by the Collateral Agent, in accordance with the Pledge
         Agreement, to satisfy in full such Corporate Units holders' obligations
         to pay the Purchase Price for the Common Stock under the related
         Purchase Contracts on the Purchase Contract Settlement Date. Any
         proceeds in excess of those required to pay the Purchase Price and the
         Remarketing Fee will be remitted to the Agent for payment to the
         Holders of the related Corporate Units. Corporate Units Holders whose
         Debentures are so remarketed will not otherwise be responsible for the
         payment of any Remarketing Fee in connection therewith. If, in spite of
         using its reasonable efforts, the Remarketing Agent cannot remarket the
         related Debentures (other than to the Company) of such Holders of
         Corporate Units at a price not less than 100% of the aggregate
         principal amount of the Debentures, the remarketing will be deemed to
         have failed (a "Failed Secondary Remarketing") and in accordance with
         the terms of the Pledge Agreement the Collateral Agent for the benefit
         of the Company will exercise its rights as a secured party with respect
         to such Debentures, including those actions specified in paragraph (c)
         below. The Company will cause a notice of such Failed Secondary
         Remarketing to be published on the second Business Day immediately
         preceding the Purchase Contract Settlement Date in a daily newspaper in
         the English language of general circulation in The City of New York,
         which is expected to be The Wall Street Journal.

                  (c) With respect to any Debentures beneficially owned by
         Holders who have elected Cash Settlement but failed to deliver cash as
         required in (a)(ii) above, or with respect to Debentures which are
         subject to a Failed Secondary Remarketing, the Collateral Agent for the
         benefit of the Company reserves all of its rights as a secured party
         with respect thereto and, subject to applicable law and paragraph (h)
         below, may, among other things, (i) retain the Debentures in full
         satisfaction of the Holders obligations under the Purchase Contracts or
         (ii) sell the Debentures in one or more public or private sales.


                                       46
<PAGE>   52
                  (d) Unless a Termination Event or an Early Settlement has
         occurred, the Purchase Contract underlying each Treasury Unit and, if a
         Tax Event Redemption or a Successful Initial Remarketing has occurred,
         each Corporate Unit will be settled with the Proceeds at maturity of
         the Treasury Security or the Applicable Ownership Interest (as defined
         in clause (A) of the definition of such term) of the Treasury
         Portfolio, as applicable. Upon receipt of such Proceeds, the Collateral
         Agent will invest the Proceeds promptly in Permitted Investments and
         pay the Proceeds to the Company on the Purchase Contract Settlement
         Date in accordance with the terms of this Agreement and the Pledge
         Agreement. Any such Proceeds received by the Collateral Agent in excess
         of the Purchase Price and any funds received by the Collateral Agent in
         respect of the investment earnings from the investment in such
         Permitted Investments will be distributed to the Agent when received
         for payment to the Holder.

                  (e) Any distribution to Holders of excess funds and interest
         described above, shall be payable at the New York Office maintained for
         that purpose or, at the option of the Holder, by check mailed to the
         address of the Person entitled thereto at such address as it appears on
         the Register.

                  (f) Unless a Holder settles the underlying Purchase Contract
         through the Early Settlement in the manner described in Section 5.9,
         the Company shall not be obligated to issue any shares of Common Stock
         in respect of a Purchase Contract or deliver any certificate therefor
         to the Holder unless it shall have received payment in full of the
         Purchase Price for the shares of Common Stock to be purchased
         thereunder in the manner set forth in this Section 5.4.

                  (g) Upon Cash Settlement of any Purchase Contract, (i) the
         Collateral Agent will in accordance with the terms of the Pledge
         Agreement cause the pledged Debentures underlying the relevant Security
         to be released from the Pledge by the Collateral Agent free and clear
         of any security interest of the Company and transferred to the Agent
         for delivery to the Holder thereof or its designee as soon as
         practicable and (ii) subject to the receipt thereof from the Collateral
         Agent, the Agent shall, by book-entry transfer, or other appropriate
         procedures, in accordance with instructions provided by the Holder
         thereof, transfer such Debentures (or, if no such instructions are
         given to the Agent by the Holder, the Agent shall hold such Debentures
         and any distributions thereon in the name of the Agent or its nominee
         in trust for the benefit of such Holder).



                                       47
<PAGE>   53

                  (h) The obligations of the Holders to pay the Purchase Price
         are non-recourse obligations and are payable solely out of any Cash
         Settlement or the Proceeds of any Collateral pledged to secure the
         obligations of the Holders and in no event will Holders be liable for
         any deficiency between the Proceeds of Collateral and the Purchase
         Price.

Section 5.5.      Issuance of Shares of Common Stock.

         Unless a Termination Event or an Early Settlement shall have occurred,
on the Purchase Contract Settlement Date, upon its receipt of payment in full of
the Purchase Price for the shares of Common Stock purchased by the Holders
pursuant to the foregoing provisions of this Article and subject to Section
5.6(c), the Company shall issue and deposit with the Agent, for the benefit of
the Holders of the Outstanding Securities, one or more certificates
representing newly issued shares of Common Stock registered in the name of the
Agent (or its nominee) as custodian for the Holders (such certificates for
shares of Common Stock, together with any dividends or distributions for which
both a record date and payment date for such dividend or distribution has
occurred on or after the Purchase Contract Settlement Date, being hereinafter
referred to as the "Purchase Contract Settlement Fund") to which the Holders are
entitled hereunder. Subject to the foregoing, upon surrender of a Certificate to
the Agent on or after the Purchase Contract Settlement Date, together with
settlement instructions thereon duly completed and executed, the Holder of such
Certificate shall be entitled to receive in exchange therefor a certificate
representing that number of whole shares of Common Stock which such Holder is
entitled to receive pursuant to the provisions of this Article Five (after
taking into account all Securities then held by such Holder) together with cash
in lieu of fractional shares as provided in Section 5.10 and any dividends or
distributions with respect to such shares constituting part of the Purchase
Contract Settlement Fund, but without any interest thereon, and the Certificate
so surrendered shall forthwith be cancelled. Such shares shall be registered in
the name of the Holder or the Holder's designee as specified in the settlement
instructions provided by the Holder to the Agent. If any shares of Common Stock
issued in respect of a Purchase Contract are to be registered to a Person other
than the Person in whose name the Certificate evidencing such Purchase Contract
is registered, no such registration shall be made unless the Person requesting
such registration has paid any transfer and other taxes required by reason of
such registration in a name other than that of the registered Holder of the
Certificate evidencing such Purchase Contract or has established to the
satisfaction of the Company that such tax either has been paid or is not
payable.



                                       48
<PAGE>   54

Section 5.6.      Adjustment of Settlement Rate.

         (a)      Adjustments for Dividends, Distributions, Stock Splits, Etc.

                  (1) In case the Company shall pay or make a dividend or other
distribution on the Common Stock and Class A Common Stock in Common Stock or
Class A Common Stock, the Settlement Rate, as in effect at the opening of
business on the day following the date fixed for the determination of
stockholders entitled to receive such dividend or other distribution shall be
increased by dividing such Settlement Rate by a fraction of which the numerator
shall be the number of shares of Common Stock and Class A Common Stock
outstanding at the close of business on the date fixed for such determination
and the denominator shall be the sum of such number of shares and the total
number of shares constituting such dividend or other distribution, such increase
to become effective immediately after the opening of business on the day
following the date fixed for such determination. For the purposes of this
paragraph (1), the number of shares of Common Stock and Class A Common Stock at
any time outstanding shall not include shares held in the treasury of the
Company but shall include any shares issuable in respect of any scrip
certificates issued in lieu of fractions of shares of Common Stock and Class A
Common Stock. The Company will not pay any dividend or make any distribution on
shares of Common Stock or Class A Common Stock held in the treasury of the
Company.

                  (2) In case the Company shall issue rights, options or
warrants to all holders of its Common Stock and Class A Common Stock (not being
available on an equivalent basis to Holders of the Securities upon settlement of
the Purchase Contracts underlying such Securities) entitling them, for a period
expiring within 45 days after the record date for the determination of
stockholders entitled to receive such rights, options or warrants, to subscribe
for or purchase shares of Common Stock or Class A Common Stock at a price per
share less than the Current Market Price per share of the Common Stock on the
date fixed for the determination of stockholders entitled to receive such
rights, options or warrants (other than pursuant to a dividend reinvestment plan
or share purchase plan), the Settlement Rate in effect at the opening of
business on the day following the date fixed for such determination shall be
increased by dividing such Settlement Rate by a fraction of which the numerator
shall be the number of shares of Common Stock and Class A Common Stock
outstanding at the close of business on the date fixed for such determination
plus the number of shares of Common Stock which the aggregate offering price of
the total number of shares of Common Stock or Class A Common Stock so offered
for subscription or purchase would purchase at such Current Market



                                       49
<PAGE>   55

Price and the denominator shall be the number of shares of Common Stock and
Class A Common Stock outstanding at the close of business on the date fixed for
such determination plus the number of shares of Common Stock or Class A Common
Stock so offered for subscription or purchase, such increase to become effective
immediately after the opening of business on the day following the date fixed
for such determination. For the purposes of this paragraph (2), the number of
shares of Common Stock and Class A Common Stock at any time outstanding shall
not include shares held in the treasury of the Company but shall include any
shares issuable in respect of any scrip certificates issued in lieu of fractions
of shares of Common Stock or Class A Common Stock. The Company shall not issue
any such rights, options or warrants in respect of shares of Common Stock or
Class A Common Stock held in the treasury of the Company.

                  (3) In case outstanding shares of Common Stock and Class A
Common Stock shall be subdivided or split into a greater number of shares of
Common Stock and Class A Common Stock, the Settlement Rate in effect at the
opening of business on the day following the day upon which such subdivision or
split becomes effective shall be proportionately increased, and, conversely, in
case outstanding shares of Common Stock and Class A Common Stock shall each be
combined into a smaller number of shares of Common Stock and Class A Common
Stock, the Settlement Rate in effect at the opening of business on the day
following the day upon which such combination becomes effective shall be
proportionately reduced, such increase or reduction, as the case may be, to
become effective immediately after the opening of business on the day following
the day upon which such subdivision, split or combination becomes effective.

                  (4) In case the Company shall, by dividend or otherwise,
distribute to all holders of its Common Stock and Class A Common Stock
evidences of its indebtedness, shares of capital stock, securities, cash or
other property (but excluding any rights or warrants referred to in paragraph
(2) of this Section, any dividend or distribution paid exclusively in cash and
any dividend or distribution referred to in paragraph (1) of this Section), the
Settlement Rate shall be increased so that the same shall equal the rate
determined by dividing the Settlement Rate in effect immediately prior to the
close of business on the date fixed for the determination of stockholders
entitled to receive such distribution by a fraction of which the numerator shall
be the Current Market Price per share of the Common Stock on the date fixed for
such determination less the then fair market value (as determined by the Board
of Directors, whose determination shall be conclusive and described in a Board
Resolution filed with the Agent) on such date of the portion of the evidences of
indebtedness, shares of capital stock, securities, cash or other property so
distributed



                                       50
<PAGE>   56

applicable to one share of Common Stock and the denominator shall be such
Current Market Price per share of the Common Stock, such adjustment to become
effective immediately prior to the opening of business on the day following the
date fixed for the determination of stockholders entitled to receive such
distribution. In any case in which this paragraph (4) is applicable, paragraph
(2) of this Section shall not be applicable.

                  (5) In case the Company shall, (I) by dividend or otherwise,
distribute to all holders of its Common Stock and Class A Common Stock cash
(excluding (i) any cash that is distributed in a Reorganization Event to which
Section 5.6(c) applies or (ii) cash that is distributed as part of a
distribution referred to in paragraph (4) of this Section) in an aggregate
amount that, combined together with (II) the aggregate amount of any other
distributions to all holders of its Common Stock and Class A Common Stock made
exclusively in cash within the 12 months preceding the date of payment of such
distribution and in respect of which no adjustment pursuant to this paragraph
(5) or paragraph (6) of this Section has been made and (III) the aggregate of
any cash plus the fair market value, as of the expiration of the applicable
tender or exchange offer referred to below (as determined by the Board of
Directors, whose determination shall be conclusive and described in a Board
Resolution), of consideration payable in respect of any tender or exchange offer
(other than consideration payable in respect of any odd-lot tender offer) by the
Company or any of its subsidiaries for all or any portion of the Common Stock or
Class A Common Stock concluded within the 12 months preceding the date of
payment of the distribution described in clause (I) above and in respect of
which no adjustment pursuant to this paragraph (5) or paragraph (6) of this
Section has been made, exceeds 15% of the product of the Current Market Price
per share of the Common Stock on the date for the determination of holders of
shares of Common Stock entitled to receive such distribution times the number of
shares of Common Stock and Class A Common Stock outstanding on such date, then,
and in each such case, immediately after the close of business on such date for
determination, the Settlement Rate shall be increased so that the same shall
equal the rate determined by dividing the Settlement Rate in effect immediately
prior to the close of business on the date fixed for determination of the
stockholders entitled to receive such distribution by a fraction (i) the
numerator of which shall be equal to the Current Market Price per share of the
Common Stock on the date fixed for such determination less an amount equal to
the quotient of (x) the combined amount distributed or payable in the
transactions described in clauses (I), (II) and (III) above and (y) the number
of shares of Common Stock and Class A Common Stock outstanding on such date for
determination and (ii) the denominator of which shall be



                                       51
<PAGE>   57

equal to the Current Market Price per share of the Common Stock on such date for
determination.

                  (6) In case (I) a tender or exchange offer made by the Company
or any subsidiary of the Company for all or any portion of the Common Stock or
Class A Common Stock shall expire and such tender or exchange offer (as amended
upon the expiration thereof) shall require the payment to stockholders (based on
the acceptance (up to any maximum specified in the terms of the tender or
exchange offer) of Purchased Shares) of an aggregate consideration having a fair
market value (as determined by the Board of Directors, whose determination shall
be conclusive and described in a Board Resolution) that combined together with
(II) the aggregate of the cash plus the fair market value (as determined by the
Board of Directors, whose determination shall be conclusive and described in a
Board Resolution), as of the expiration of such tender or exchange offer, of
consideration payable in respect of any other tender or exchange offer (other
than consideration payable in respect of any odd-lot tender offer) by the
Company or any subsidiary of the Company for all or any portion of the Common
Stock or Class A Common Stock expiring within the 12 months preceding the
expiration of such tender or exchange offer and in respect of which no
adjustment pursuant to paragraph (5) of this Section or this paragraph (6) has
been made and (III) the aggregate amount of any distributions to all holders of
the Company's Common Stock and Class A Common Stock made exclusively in cash
within the 12 months preceding the expiration of such tender or exchange offer
and in respect of which no adjustment pursuant to paragraph (5) of this Section
or this paragraph (6) has been made, exceeds 15% of the product of the Current
Market Price per share of the Common Stock as of the last time (the "Expiration
Time") tenders could have been made pursuant to such tender or exchange offer
(as it may be amended) times the number of shares of Common Stock and Class A
Common Stock outstanding (including any tendered shares) on the Expiration Time,
then, and in each such case, immediately prior to the opening of business on the
day after the date of the Expiration Time, the Settlement Rate shall be adjusted
so that the same shall equal the rate determined by dividing the Settlement Rate
immediately prior to the close of business as of the Expiration Time by a
fraction (i) the numerator of which shall be equal to (A) the product of (I) the
Current Market Price per share of the Common Stock as of the Expiration Time and
(II) the number of shares of Common Stock and Class A Common Stock outstanding
(including any tendered shares) as of the Expiration Time less (B) the amount of
cash plus the fair market value (determined as aforesaid) of the aggregate
consideration payable to stockholders based on the transactions described in
clauses (I), (II) and (III) above (assuming in the case of clause (I) the
acceptance, up to any maximum specified in the terms of the tender or exchange
offer, of Purchased Shares), and (ii) the denominator of which



                                       52
<PAGE>   58

shall be equal to the product of (A) the Current Market Price per share of the
Common Stock as of the Expiration Time and (B) the number of shares of Common
Stock and Class A Common Stock outstanding (including any tendered shares) as of
the Expiration Time less the number of all shares validly tendered and not
withdrawn as of the Expiration Time (the shares deemed so accepted, up to any
such maximum, being referred to as the "Purchased Shares").

                  (7) The issuance or distribution by the Company of its
securities in connection with any exchange offer, recapitalization,
reorganization or similar transaction (a "Recapitalization Transaction")
effected by the Company in order to facilitate a tax-free distribution by Xcel
Energy Inc. of its interest in the Company will not be deemed to require an
adjustment to the Settlement Rate pursuant to paragraphs (1)-(6) of this
Section, provided that (i) the securities issued or distributed in respect of
any share of Common Stock in such Recapitalization Transaction do not represent
an economic interest in the Company that is greater than the economic interest
in the Company represented by a share of Common Stock immediately prior to the
consummation of such Recapitalization Transaction and (ii) the Company does not
pay a cash premium to any holders of Common Stock in connection with such
transaction.

                  (8) The "Current Market Price" per share of Common Stock on
any day means the average of the daily Closing Prices for the five consecutive
Trading Days selected by the Company commencing not more than 30 Trading Days
before, and ending not later than, the earlier of the day in question and the
day before the "ex date" with respect to the issuance or distribution requiring
such computation. For purposes of this paragraph, the term "ex date", when used
with respect to any issuance or distribution, shall mean the first date on which
the Common Stock trades regular way on such exchange or in such market without
the right to receive such issuance or distribution.

                  (9) All adjustments to the Settlement Rate, shall be
calculated to the nearest 1/10,000th of a share of Common Stock (or if there is
not a nearest 1/10,000th of a share to the next lower 1/10,000th of a share). No
adjustment in the Settlement Rate shall be required unless such adjustment would
require an increase or decrease of at least one percent therein; provided,
however, that any adjustments which by reason of this subparagraph are not
required to be made shall be carried forward and taken into account in any
subsequent adjustment. [If an adjustment is made to the Settlement Rate pursuant
to paragraph (1), (2), (3), (4), (5), (6), (7) or (10) of this Section 5.6(a),
an adjustment shall also be made to the Applicable Market Value solely to
determine which of clauses (a), (b) or (c) of the definition of



                                       53
<PAGE>   59

Settlement Rate in Section 5.1 will apply on the Purchase Contract Settlement
Date. Such adjustment shall be made by multiplying the Applicable Market Value
by a fraction of which the numerator shall be the Settlement Rate immediately
after such adjustment pursuant to paragraph (1), (2), (3), (4), (5), (6), (7) or
(10) of this Section 5.6(a) and the denominator shall be the Settlement Rate
immediately before such adjustment; provided, however, that if such adjustment
to the Settlement Rate is required to be made pursuant to the occurrence of any
of the events contemplated by paragraph (1), (2), (3), (4), (5), (7) or (10) of
this Section 5.6(a) during the period taken into consideration for determining
the Applicable Market Value, appropriate and customary adjustments shall be made
to the Settlement Rate.]

                  (10) The Company may make such increases in the Settlement
Rate, in addition to those required by this Section, as it considers to be
advisable in order to avoid or diminish any income tax to any holders of shares
of Common Stock resulting from any dividend or distribution of stock or issuance
of rights or warrants to purchase or subscribe for stock or from any event
treated as such for income tax purposes or for any other reasons.

         (b)      Adjustment for Certain Recapitalization Transactions.

                  (1) If the Company completes a Recapitalization Transaction
pursuant to which some, but not all, of the shares of Common Stock outstanding
immediately prior to such transaction are exchanged for or converted, changed or
reclassified into other Common Equity Securities, then thereafter each Holder of
Securities will receive on the Purchase Contract Settlement Date with respect to
each Purchase Contract forming a part thereof, at such Holder's election, either
(i) shares of Common Stock at a Settlement Rate equal to the Settlement Rate in
effect immediately prior to such Recapitalization Transaction as adjusted in
accordance with subsection (a) of this Section 5.6 (A) for any premium paid to
holders of Common Stock in such Recapitalization Transaction other than in the
form of such other Common Equity Securities representing a greater economic
interest in the Company than the shares of Common Stock in respect of which such
Common Equity Securities were issued (but without adjustment for any such
premium paid in the form of such other Common Equity Securities) and (B) for any
transactions or events occurring after such Recapitalization Transaction that
require an adjustment to the Settlement Rate under subsection (a) of this
Section 5.6 or (ii) shares of such other Common Equity Securities at a
Settlement Rate determined under Section 5.1 based on the Applicable Market
Value of such other Common Equity Securities and equal to the Settlement Rate in
effect immediately prior to such Recapitalization Transaction multiplied by the
number of such other Common Equity Securities




                                       54
<PAGE>   60

issued in respect of one share of Common Stock in such Recapitalization
Transaction and as adjusted in accordance with subsection (a) of this Section
5.6 (A) for any premium paid to holders of Common Stock in such Recapitalization
Transaction other than in the form of such other Common Equity Securities and
(B) for any transactions or events occurring after such Recapitalization
Transaction that require an adjustment to the Settlement Rate under subsection
(a) of this Section 5.6, with the provisions of such subsection applying to
events relating to such other Common Equity Securities to the same extent as
they apply to events relating to the Common Stock. In the event that any
Recapitalization Transaction of the type contemplated by this paragraph (1)
occurs, the Company shall, at least 30 Business Days prior to the Purchase
Contract Settlement Date, provide each Holder with an election form pursuant to
which the Holder may elect to receive either Common Stock or the other Common
Equity Securities upon settlement of the Purchase Contracts as provided in this
paragraph (1). Any Holder for whom the Company has not received a completed
election form on or before the Business Day immediately preceding the Purchase
Contract Settlement Date will be deemed to have elected to receive Common Stock.

                  (2) If the Company completes a Recapitalization Transaction
pursuant to which all of the shares of Common Stock outstanding immediately
prior to such transaction are exchanged for or converted, changed or
reclassified into shares of other Common Equity Securities, then thereafter each
Holder of Securities will receive on the Purchase Contract Settlement Date with
respect to each Purchase Contract forming a part thereof only such other Common
Equity Securities at a Settlement Rate determined under Section 5.1 based on the
Applicable Market Value of such other Common Equity Securities and equal to the
Settlement Rate in effect immediately prior to such Recapitalization Transaction
multiplied by the number of such other Common Equity Securities issued in
respect of one share of Common Stock in such Recapitalization Transaction and as
adjusted in accordance with subsection (a) of this Section 5.6 (A) for any
premium paid to holders of Common Stock in such Recapitalization Transaction
other than in the form of such other Common Equity Securities and (B) for any
transactions or events occurring after such Recapitalization Transaction that
require an adjustment to the Settlement Rate under subsection (a) of this
Section 5.6, with the provisions of such subsection applying to events relating
to such other Common Equity Securities to the same extent as they apply to
events relating to the Common Stock.

         (c) Adjustment for Consolidation, Merger or Other Reorganization Event.
In the event of (i) any Recapitalization Transaction pursuant to which all
outstanding shares of Common Stock are exchanged for or converted, changed or
reclassified into cash, securities or other property not including Common Equity
Securities, (ii)



                                       55
<PAGE>   61

any consolidation or merger of the Company with or into another Person (other
than a merger or consolidation in which the Company is the continuing
corporation and in which the Common Stock outstanding immediately prior to the
merger or consolidation is not exchanged for cash, securities or other property
of the Company or another corporation), (iii) any sale, transfer, lease or
conveyance to another Person of the property of the Company as an entirety or
substantially as an entirety, (iv) any statutory exchange of securities of the
Company with another Person (other than in connection with a merger or
acquisition) or (v) any liquidation, dissolution or winding up of the Company
other than as a result of or after the occurrence of a Termination Event (any
such event, a "Reorganization Event"), the Settlement Rate will be adjusted to
provide that each Holder of Securities will receive on the Purchase Contract
Settlement Date with respect to each Purchase Contract forming a part thereof
(or upon any Early Settlement), the kind and amount of securities, cash and
other property receivable upon such Reorganization Event (without any interest
thereon, and without any right to dividends or distribution thereon which have a
record date that is prior to the Purchase Contract Settlement Date) by a Holder
of the number of shares of Common Stock issuable on account of each Purchase
Contract if the Purchase Contract Settlement Date had occurred immediately prior
to such Reorganization Event assuming such Holder of Common Stock is not a
Person with which the Company consolidated or into which the Company merged or
which merged into the Company or to which such sale or transfer was made, as the
case may be (any such Person, a "Constituent Person"), or an Affiliate of a
Constituent Person to the extent such Reorganization Event provides for
different treatment of Common Stock held by Affiliates of the Company and
non-affiliates and such Holder failed to exercise its rights of election, if
any, as to the kind or amount of securities, cash and other property receivable
upon such Reorganization Event (provided that if the kind or amount of
securities, cash and other property receivable upon such Reorganization Event is
not the same for each share of Common Stock held immediately prior to such
Reorganization Event by other than a Constituent Person or an Affiliate thereof
and in respect of which such rights of election shall not have been exercised
("non-electing share"), then for the purpose of this Section the kind and amount
of securities, cash and other property receivable upon such Reorganization
Event by each non-electing share shall be deemed to be the kind and amount so
receivable per share by the non-electing shares). In the event of such a
Reorganization Event described in clauses (ii)-(v) above, the Person formed by
such consolidation, merger or exchange or the Person which acquires or leases
the assets of the Company or, in the event of a liquidation or dissolution of
the Company, the Company or a liquidating trust created in connection therewith,
shall execute and deliver to the Agent an agreement supplemental hereto
providing that the Holders of each Outstanding Security shall have the rights
provided by this Section 5.6. Such




                                       56
<PAGE>   62
supplemental agreement shall provide for adjustments which, for events
subsequent to the effective date of such supplemental agreement, shall be as
nearly equivalent as may be practicable to the adjustments provided for in this
Section. In the event of a Reorganization Event described in clause (i) above,
the adjustment provisions of this Section shall apply to the extent practicable
to any securities issued in the Recapitalization Transaction. The above
provisions of this Section shall similarly apply to successive Reorganization
Events.

Section 5.7.      Notice of Adjustments and Certain Other Events.

         (a)      Whenever the Settlement Rate is adjusted as herein provided,
the Company shall:

                  (i) forthwith compute the Settlement Rate in accordance with
         Section 5.6 and prepare and transmit to the Agent an Officer's
         Certificate setting forth the Settlement Rate, the method of
         calculation thereof in reason able detail, and the facts requiring such
         adjustment and upon which such adjustment is based; and

                  (ii) within 10 Business Days following the occurrence of an
         event that requires an adjustment to the Settlement Rate pursuant to
         Section 5.6 (or if the Company is not aware of such occurrence, as soon
         as practicable after becoming so aware), provide a written notice to
         the Holders of the Securities of the occurrence of such event and a
         statement in reasonable detail setting forth the method by which the
         adjustment to the Settlement Rate was deter mined and setting forth the
         adjusted Settlement Rate.

         (b) The Agent shall not at any time be under any duty or responsibility
to any Holder of Securities to determine whether any facts exist which may
require any adjustment of the Settlement Rate, or with respect to the nature or
extent or calculation of any such adjustment when made, or with respect to the
method employed in making the same. The Agent shall not be accountable with
respect to the validity or value (or the kind or amount) of any shares of Common
Stock, or of any securities or property, which may at the time be issued or
delivered with respect to any Purchase Contract; and the Agent makes no
representation with respect thereto. The Agent shall not be responsible for any
failure of the Company to issue, transfer or deliver any shares of Common Stock
pursuant to a Purchase Contract or to comply with any of the duties,
responsibilities or covenants of the Company contained in this Article.


                                       57
<PAGE>   63

Section 5.8.      Termination Event; Notice.

         The Purchase Contracts and all obligations and rights of the Company
and the Holders thereunder, including, without limitation, the rights and
obligations of Holders to purchase Common Stock, shall immediately and
automatically terminate, without the necessity of any notice or action by any
Holder, the Agent or the Company, if, on or prior to the Purchase Contract
Settlement Date, a Termination Event shall have occurred. Upon and after the
occurrence of a Termination Event, the Securities shall thereafter represent the
right to receive the Debentures or the appropriate Applicable Ownership Interest
of the Treasury Portfolio, as the case may be, forming a part of such Securities
in the case of Corporate Units, or Treasury Securities in the case of Treasury
Units, in accordance with the provisions of Section 4.3 of the Pledge Agreement;
provided, however, that, to the extent that a Holder of Corporate Units or
Treasury Units would otherwise be entitled to receive less than $1,000 principal
amount at maturity of the Treasury Portfolio or the Treasury Securities, the
Agent shall dispose of such securities for cash, and transfer the appropriate
amount of such cash to such Holder in accordance with such Holder's
instructions. Upon the occurrence of a Termination Event, the Company shall
promptly but in no event later than two Business Days thereafter give written
notice to the Agent, the Collateral Agent and to the Holders, at their addresses
as they appear in the Register.

Section 5.9.      Early Settlement.

         (a) Subject to and upon compliance with the provisions of this Section
5.9, at the option of the Holder thereof, Purchase Contracts underlying
Securities having an aggregate Stated Amount equal to $1,000 or an integral
multiple thereof may be settled early ("Early Settlement") in the case of
Corporate Units (unless a Tax Event Redemption or a Successful Initial
Remarketing has occurred) on or prior to the fifth Business Day immediately
preceding the Purchase Contract Settlement Date and in the case of Treasury
Units on or prior to the second Business Day immediately preceding the Purchase
Contract Settlement Date, in each case, as provided herein; provided however,
that if a Tax Event Redemption or a Successful Initial Remarketing has occurred
and the Treasury Portfolio has become a component of the Corporate Units,
Purchase Contracts underlying Corporate Units may be settled early on or prior
to the second Business Day immediately preceding the Purchase Contract
Settlement Date, but only in an aggregate amount of ____ Corporate Units or in
an integral multiple thereof. In order to exercise the right to effect Early
Settlement with respect to any Purchase Contracts, the Holder of the Certificate
evidencing Securities shall deliver such Certificate to the Agent at the
Corporate Trust Office or



                                       58
<PAGE>   64
the New York Office duly endorsed for transfer to the Company or in blank with
the form of Election to Settle Early on the reverse thereof duly completed and
accompanied by payment (payable to the Company) in immediately available funds
in an amount (the "Early Settlement Amount") equal to the product of (i) the
Stated Amount times (ii) the number of Purchase Contracts with respect to which
the Holder has elected to effect Early Settlement. No payment or adjustment
shall be made upon Early Settlement of any Purchase Contract on account of any
dividends on the Common Stock issued upon such Early Settlement. If the
foregoing requirements are first satisfied with respect to Purchase Contracts
underlying any Securities at or prior to 5:00 p.m., New York City time, on a
Business Day, such day shall be the "Early Settlement Date" with respect to such
Securities and if such requirements are first satisfied after 5:00 p.m., New
York City time, on a Business Day or on a day that is not a Business Day, the
"Early Settlement Date" with respect to such Securities shall be the next
succeeding Business Day.

         (b) Upon Early Settlement of Purchase Contracts by a Holder of the
related Securities and payment of any transfer or similar taxes payable by such
Holder in connection with the issuance of the related Common Stock to any person
other than such Holder, the Company shall issue, and the Holder shall be
entitled to receive, _____ shares of newly issued Common Stock on account of
each Purchase Contract as to which Early Settlement is effected (the "Early
Settlement Rate"). The Early Settlement Rate shall be adjusted in the same
manner and at the same time as the Settlement Rate is adjusted. As promptly as
practicable after Early Settlement of Purchase Contracts in accordance with the
provisions of this Section 5.9, the Company shall issue and shall deliver to
the Agent at the Corporate Trust Office a certificate or certificates for the
full number of shares of Common Stock issuable upon such Early Settlement
together with payment in lieu of any fraction of a share, as provided in Section
5.10.

         (c) No later than the third Business Day after the applicable Early
Settlement Date the Company shall cause (i) the shares of Common Stock issuable
upon Early Settlement of Purchase Contracts to be issued and delivered, and (ii)
the related Debentures or the appropriate Applicable Ownership Interest of the
Treasury Portfolio, in the case of Corporate Units, or the related Treasury
Securities, in the case of Treasury Units, to be released from the Pledge by the
Collateral Agent and transferred, in each case to the Agent for delivery to the
Holder thereof or its designee.


                                       59
<PAGE>   65

         (d) Upon Early Settlement of any Purchase Contracts, and subject to
receipt of shares of Common Stock from the Company and the Debentures, the
appropriate Applicable Ownership Interest of the Treasury Portfolio or Treasury
Securities, as the case may be, from the Collateral Agent, as applicable, the
Agent shall, in accordance with the instructions provided by the Holder thereof
on the applicable form of Election to Settle Early on the reverse of the
Certificate evidencing the related Securities, (i) transfer to the Holder the
Debentures, Treasury Portfolio or Treasury Securities, as the case may be,
forming a part of such Securities, and (ii) deliver to the Holder a certificate
or certificates for the full number of shares of Common Stock issuable upon such
Early Settlement together with payment in lieu of any fraction of a share, as
provided in Section 5.10.

         (e) In the event that Early Settlement is effected with respect to
Purchase Contracts underlying less than all the Securities evidenced by a
Certificate, upon such Early Settlement the Company shall execute and the Agent
shall authenticate, countersign and deliver to the Holder thereof, at the
expense of the Company, a Certificate evidencing the Securities as to which
Early Settlement was not effected.

Section 5.10.     No Fractional Shares.

         No fractional shares or scrip representing fractional shares of Common
Stock shall be issued or delivered upon settlement on the Purchase Contract
Settlement Date or upon Early Settlement of any Purchase Contracts. If
Certificates evidencing more than one Purchase Contract shall be surrendered for
settlement at one time by the same Holder, the number of full shares of Common
Stock which shall be delivered upon settlement shall be computed on the basis of
the aggregate number of Purchase Contracts evidenced by the Certificates so
surrendered. Instead of any fractional share of Common Stock which would
otherwise be deliverable upon settlement of any Purchase Contracts on the
Purchase Contract Settlement Date or upon Early Settlement, the Company, through
the Agent, shall make a cash payment in respect of such fractional interest in
an amount equal to the value of such fractional shares times the Applicable
Market Value. The Company shall provide the Agent from time to time with
sufficient funds to permit the Agent to make all cash payments required by this
Section 5.10 in a timely manner.

Section 5.11.     Charges and Taxes.

         The Company will pay all stock transfer and similar taxes attributable
to the initial issuance and delivery of the shares of Common Stock pursuant to
the Purchase Contracts; provided, however, that the Company shall not be
required to pay any



                                       60
<PAGE>   66

such tax or taxes which may be payable in respect of any exchange of or
substitution for a Certificate evidencing a Security or any issuance of a share
of Common Stock in a name other than that of the registered Holder of a
Certificate surrendered in respect of the Securities evidenced thereby, other
than in the name of the Agent, as custodian for such Holder, and the Company
shall not be required to issue or deliver such share certificates or
Certificates unless or until the Person or Persons requesting the transfer or
issuance thereof shall have paid to the Company the amount of such tax or shall
have established to the satisfaction of the Company that such tax has been paid
or that no such tax is due.


                                   ARTICLE VI

                                    Remedies

Section 6.1.      Unconditional Right of Holders to Purchase Common Stock.

         The Holder of any Corporate Units or Treasury Units shall have the
right, which is absolute and unconditional, to purchase Common Stock pursuant to
such Purchase Contract and to institute suit for the enforcement of such right
to purchase Common Stock, and such right shall not be impaired without the
consent of such Holder.

Section 6.2.      Restoration of Rights and Remedies.

         If any Holder has instituted any proceeding to enforce any right or
remedy under this Agreement and such proceeding has been discontinued or
abandoned for any reason, or has been determined adversely to such Holder, then
and in every such case, subject to any determination in such proceeding, the
Company and such Holder shall be restored severally and respectively to their
former positions hereunder and thereafter all rights and remedies of such Holder
shall continue as though no such proceeding had been instituted.

Section 6.3.      Rights and Remedies Cumulative.

         Except as otherwise provided with respect to the replacement or payment
of mutilated, destroyed, lost or stolen Certificates in the last paragraph of
Section 3.10, no right or remedy herein conferred upon or reserved to the
Holders is intended to be exclusive of any other right or remedy, and every
right and



                                       61
<PAGE>   67

remedy shall, to the extent permitted by law, be cumulative and in addition to
every other right and remedy given hereunder or now or hereafter existing at law
or in equity or otherwise. The assertion or employment of any right or remedy
hereunder, or otherwise, shall not prevent the concurrent assertion or
employment of any other appropriate right or remedy.

Section 6.4.      Delay or Omission Not Waiver.

         No delay or omission of any Holder to exercise any right or remedy upon
a default shall impair any such right or remedy or constitute a waiver of any
such right. Every right and remedy given by this Article or by law to the
Holders may be exercised from time to time, and as often as may be deemed
expedient, by such Holders.

Section 6.5.      Undertaking for Costs.

         All parties to this Agreement agree, and each Holder of Corporate Units
or Treasury Units, by its acceptance of such Corporate Units or Treasury Units
shall be deemed to have agreed, that any court may in its discretion require, in
any suit for the enforcement of any right or remedy under this Agreement, or in
any suit against the Agent for any action taken, suffered or omitted by it as
Agent, the filing by any party litigant in such suit of an undertaking to pay
the costs of such suit, and that such court may in its discretion assess
reasonable costs, including reasonable attorneys' fees, against any party
litigant in such suit, having due regard to the merits and good faith of the
claims or defenses made by such party litigant; provided that the provisions of
this Section shall not apply to any suit instituted by the Company, to any suit
instituted by the Agent, to any suit instituted by any Holder, or group of
Holders, holding in the aggregate more than 10% of the Outstanding Securities,
or to any suit instituted by any Holder for the enforcement of interest on any
Debentures on or after the respective Payment Date therefor in respect of any
Security held by such Holder, or for enforcement of the right to purchase shares
of Common Stock under the Purchase Contracts constituting part of any Security
held by such Holder.

Section 6.6.      Waiver of Stay or Extension Laws.

         The Company covenants (to the extent that it may lawfully do so) that
it will not at any time insist upon, or plead, or in any manner whatsoever claim
or take the benefit or advantage of, any stay or extension law wherever enacted,
now or at any time hereafter in force, which may affect the covenants or the
performance of this Agreement; and the Company (to the extent that it may
lawfully do so) hereby expressly waives all benefit or advantage of any such law
and covenants that it will


                                       62
<PAGE>   68


not hinder, delay or impede the execution of any power herein granted to the
Agent or the Holders, but will suffer and permit the execution of every such
power as though no such law had been enacted.

                                   ARTICLE VII

                                    The Agent

Section 7.1.      Certain Duties and Responsibilities.

         (a)      (1) The Agent undertakes to perform, with respect to the
Securities, such duties and only such duties as are specifically set forth in
this Agreement and the Pledge Agreement, and no implied covenants or obligations
shall be read into this Agreement against the Agent; and

                  (2) The Agent may, with respect to the Securities,
         conclusively rely, as to the truth of the statements and the
         correctness of the opinions expressed therein, upon certificates or
         opinions furnished to the Agent and conforming to the requirements of
         this Agreement, but in the case of any certificates or opinions which
         by any provision hereof are specifically required to be furnished to
         the Agent, the Agent shall be under a duty to examine the same to
         determine whether or not they conform to the requirements of this
         Agreement, but need not confirm or investigate the accuracy of
         mathematical calculations stated therein.

         (b) No provision of this Agreement shall be construed to relieve the
Agent from liability for its own negligent action, its own negligent failure to
act, or its own wilful misconduct or bad faith, except that

                  (1) this Subsection shall not be construed to limit the effect
         of Subsection (a) of this Section;

                  (2) the Agent shall not be liable for any error of judgment
         made in good faith by a Responsible Officer, unless it shall be proved
         that the Agent was negligent in ascertaining the pertinent facts; and

                  (3) no provision of this Agreement shall require the Agent to
         expend or risk its own funds or otherwise incur any financial liability
         in the


                                       63
<PAGE>   69


         performance of any of its duties hereunder, or in the exercise of any
         of its rights or powers.

         (c) Whether or not therein expressly so provided, every provision of
this Agreement relating to the conduct or affecting the liability of or
affording protection to the Agent shall be subject to the provisions of this
Section.

         (d) The Agent is authorized to execute and deliver the Pledge Agreement
in its capacity as Agent.

Section 7.2.      Notice of Default.

         Within 30 days after the occurrence of any default by the Company
hereunder of which a Responsible Officer of the Agent has actual knowledge, the
Agent shall transmit by mail to the Company and the Holders of Securities, as
their names and addresses appear in the Register, notice of such default
hereunder, unless such default shall have been cured or waived.

Section 7.3.      Certain Rights of Agent.

         Subject to the provisions of Section 7.1:

         (a) the Agent may rely and shall be protected in acting or refraining
from acting upon any resolution, certificate, statement, instrument, opinion,
report, notice, request, direction, consent, order, bond, debenture, note, other
evidence of indebtedness or other paper or document believed by it to be genuine
and to have been signed or presented by the proper party or parties;

         (b) any request or direction of the Company mentioned herein shall be
sufficiently evidenced by an Officer's Certificate, Issuer Order or Issuer
Request, and any resolution of the Board of Directors of the Company may be
sufficiently evidenced by a Board Resolution;

         (c) whenever in the administration of this Agreement the Agent shall
deem it desirable that a matter be proved or established prior to taking,
suffering or omitting any action hereunder, the Agent (unless other evidence be
herein specifically prescribed) may, in the absence of bad faith on its part,
rely upon an Officer's Certificate of the Company;



                                       64
<PAGE>   70

         (d) the Agent may consult with counsel of its selection and the advice
of such counsel or any Opinion of Counsel shall be full and complete
authorization and protection in respect of any action taken, suffered or omitted
by it hereunder in good faith and in reliance thereon;

         (e) the Agent shall not be bound to make any investigation into the
facts or matters stated in any resolution, certificate, statement, instrument,
opinion, report, notice, request, direction, consent, order, bond, debenture,
note, other evidence of indebtedness or other paper or document, but the Agent,
in its discretion, may make reasonable further inquiry or investigation into
such facts or matters related to the execution, delivery and performance of the
Purchase Contracts as it may see fit, and, if the Agent shall determine to make
such further inquiry or investigation, it shall be given a reasonable
opportunity to examine the books, records and premises of the Company,
personally or by agent or attorney; and

         (f) the Agent may execute any of the powers hereunder or perform any
duties hereunder either directly or by or through agents or attorneys or an
Affiliate and the Agent shall not be responsible for any misconduct or
negligence on the part of any agent or attorney or an Affiliate appointed with
due care by it hereunder.

Section 7.4.      Not Responsible for Recitals or Issuance of Securities.

         The recitals contained herein and in the Certificates shall be taken as
the statements of the Company and the Agent assumes no responsibility for their
accuracy. The Agent makes no representations as to the validity or sufficiency
of either this Agreement or of the Securities, or of the Pledge Agreement or the
Pledge. The Agent shall not be accountable for the use or application by the
Company of the proceeds in respect of the Purchase Contracts.

Section 7.5.      May Hold Securities.

         Any Registrar or any other agent of the Company, or the Agent and its
Affiliates, in their individual or any other capacity, may become the owner or
pledgee of Securities and may otherwise deal with the Company, the Collateral
Agent or any other Person with the same rights it would have if it were not
Registrar or such other agent, or the Agent.

Section 7.6.      Money Held in Custody.



                                       65
<PAGE>   71

         Money held by the Agent in custody hereunder need not be segregated
from the other funds except to the extent required by law or provided herein.
The Agent shall be under no obligation to invest or pay interest on any money
received by it hereunder except as otherwise expressly provided herein or as
otherwise agreed in writing with the Company.

Section 7.7.      Compensation and Reimbursement.

         The Company agrees:

                  (1) to pay to the Agent from time to time such compensation
         for all services rendered by it hereunder as the parties shall agree
         from time to time;

                  (2) except as otherwise expressly provided herein, to
         reimburse the Agent upon its request for all reasonable expenses,
         disbursements and advances incurred or made by the Agent in accordance
         with any provision of this Agreement (including the reasonable
         compensation and the expenses and disbursements of its agents and
         counsel), except any such expense, disbursement or advance as may be
         attributable to its negligence, willful misconduct or bad faith; and

                  (3) to indemnify the Agent and any predecessor Agent for, and
         to hold it harmless against, any loss, liability or expense, including
         taxes (other than taxes based upon, measured by or determined by the
         income of the Agent) incurred without negligence, willful misconduct or
         bad faith on its part, arising out of or in connection with the
         acceptance or administration of its duties hereunder, including the
         costs and expenses of defending itself against any claim or liability
         in connection with the exercise or performance of any of its powers or
         duties hereunder.

         The provisions of this Section shall survive the termination of this
Agreement.

Section 7.8.      Corporate Agent Required; Eligibility.

         There shall at all times be an Agent hereunder which shall be a
corporation organized and doing business under the laws of the United States of
America, any State thereof or the District of Columbia, authorized under such
laws to exercise corporate trust powers, having (or being a subsidiary of a bank
holding company



                                       66
<PAGE>   72

having) a combined capital and surplus of at least $50,000,000, subject to
supervision or examination by Federal or State authority and having an office
in the Borough of Manhattan, The City of New York, if there be such a
corporation in the Borough of Manhattan, The City of New York, qualified and
eligible under this Article and willing to act on reasonable terms. If such
corporation publishes reports of condition at least annually, pursuant to law or
to the requirements of said supervising or examining authority, then for the
purposes of this Section, the combined capital and surplus of such corporation
shall be deemed to be its combined capital and surplus as set forth in its most
recent report of condition so published. If at any time the Agent shall cease to
be eligible in accordance with the provisions of this Section, it shall resign
immediately in the manner and with the effect hereinafter specified in this
Article. The provisions of this Section shall survive the termination of this
Agreement.

Section 7.9.      Resignation and Removal; Appointment of Successor.

         (a) No resignation or removal of the Agent and no appointment of a
successor Agent pursuant to this Article shall become effective until the
acceptance of appointment by the successor Agent in accordance with the
applicable requirements of Section 7.10.

         (b) The Agent may resign at any time by giving written notice thereof
to the Company 60 days prior to the effective date of such resignation. If the
instrument of acceptance by a successor Agent required by Section 7.10 shall
not have been delivered to the Agent within 30 days after the giving of such
notice of resignation, the resigning Agent may petition any court of competent
jurisdiction for the appointment of a successor Agent.

         (c) The Agent may be removed at any time by Act of the Holders of a
majority in number of the Outstanding Securities delivered to the Agent and the
Company. If the instrument of acceptance by a successor Agent required by
Section 7.10 shall not have been delivered to the Agent within 30 days after the
giving of such notice of resignation, the resigning Agent may petition any court
of competent jurisdiction for the appointment of a successor Agent.

         (d) If at any time

                  (1) the Agent fails to comply with Section 310(b) of the TIA,
         as if the Agent were an indenture trustee under an indenture qualified
         under the

                                       67
<PAGE>   73




         TIA, after written request therefor by the Company or by any Holder who
         has been a bona fide Holder of a Security for at least six months, or

                  (2) the Agent shall cease to be eligible under Section 7.8 and
         shall fail to resign after written request therefor by the Company or
         by any such Holder, or

                  (3) the Agent shall become incapable of acting or shall be ad
         judged a bankrupt or insolvent or a receiver of the Agent or of its
         property shall be appointed or any public officer shall take charge or
         control of the Agent or of its property or affairs for the purpose of
         rehabilitation, conservation or liquidation,

then, in any such case, (i) the Company by a Board Resolution may remove the
Agent, or (ii) any Holder who has been a bona fide Holder of a Security for at
least six months may, on behalf of himself and all others similarly situated,
petition any court of competent jurisdiction for the removal of the Agent and
the appointment of a successor Agent.

         (e) If the Agent shall resign, be removed or become incapable of
acting, or if a vacancy shall occur in the office of Agent for any cause, the
Company, by a Board Resolution, shall promptly appoint a successor Agent and
shall comply with the applicable requirements of Section 7.10. If no successor
Agent shall have been so appointed by the Company and accepted appointment in
the manner required by Section 7.10, any Holder who has been a bona fide Holder
of a Security for at least six months may, on behalf of himself and all others
similarly situated, petition any court of competent jurisdiction for the
appointment of a successor Agent.

         (f) The Company shall give, or shall cause such successor Agent to
give, notice of each resignation and each removal of the Agent and each
appointment of a successor Agent by mailing written notice of such event by
first-class mail, postage prepaid, to all Holders as their names and addresses
appear in the applicable Register. Each notice shall include the name of the
successor Agent and the address of its Corporate Trust Office and New York
Office, if any.

Section 7.10.     Acceptance of Appointment by Successor.

         (a) In case of the appointment hereunder of a successor Agent, every
such successor Agent so appointed shall execute, acknowledge and deliver to the
Company and to the retiring Agent an instrument accepting such appointment, and



                                       68
<PAGE>   74

thereupon the resignation or removal of the retiring Agent shall become
effective and such successor Agent, without any further act, deed or conveyance,
shall become vested with all the rights, powers, agencies and duties of the
retiring Agent; but, on the request of the Company or the successor Agent, such
retiring Agent shall, upon payment of its charges, execute and deliver an
instrument transferring to such successor Agent all the rights, powers and
trusts of the retiring Agent and shall duly assign, transfer and deliver to such
successor Agent all property and money held by such retiring Agent hereunder.

         (b) Upon request of any such successor Agent, the Company shall execute
any and all instruments for more fully and certainly vesting in and confirming
to such successor Agent all such rights, powers and agencies referred to in
paragraph (a) of this Section.

         (c) No successor Agent shall accept its appointment unless at the time
of such acceptance such successor Agent shall be qualified and eligible under
this Article.

Section 7.11.     Merger, Conversion, Consolidation or Succession to Business.

         Any corporation into which the Agent may be merged or converted or with
which it may be consolidated, or any corporation resulting from any merger,
conversion or consolidation to which the Agent shall be a party, or any
corporation succeeding to all or substantially all the corporate trust business
of the Agent, shall be the successor of the Agent hereunder, provided such
corporation shall be otherwise qualified and eligible under this Article,
without the execution or filing of any paper or any further act on the part of
any of the parties hereto. In case any Certificates shall have been
authenticated and executed on behalf of the Holders, but not delivered, by the
Agent then in office, any successor by merger, conversion or consolidation to
such Agent may adopt such authentication and execution and deliver the
Certificates so authenticated and executed with the same effect as if such
successor Agent had itself authenticated and executed such Securities.

Section 7.12.     Preservation of Information; Communications to Holders.

         (a) The Agent shall preserve, in as current a form as is reasonably
practicable, the names and addresses of Holders received by the Agent in its
capacity as Registrar.



                                       69
<PAGE>   75

         (b) If three or more Holders (herein referred to as "applicants") apply
in writing to the Agent, and furnish to the Agent reasonable proof that each
such applicant has owned a Security for a period of at least six months
preceding the date of such application, and such application states that the
applicants desire to communicate with other Holders with respect to their
rights under this Agreement or under the Securities and is accompanied by a copy
of the form of proxy or other communication which such applicants propose to
transmit, then the Agent shall mail to all the Holders copies of the form of
proxy or other communication which is specified in such request, with reasonable
promptness after a tender to the Agent of the materials to be mailed and of
payment, or provision for the payment, of the reasonable expenses of such
mailing.

Section 7.13.     No Obligations of Agent.

         Except to the extent otherwise provided in this Agreement, the Agent
assumes no obligations and shall not be subject to any liability under this
Agreement, the Pledge Agreement or any Purchase Contract in respect of the
obligations of the Holder of any Security thereunder. The Company agrees, and
each Holder of a Certificate, by his acceptance thereof, shall be deemed to have
agreed, that the Agent's execution of the Certificates on behalf of the Holders
shall be solely as agent and attorney-in-fact for the Holders, and that the
Agent shall have no obligation to perform such Purchase Contracts on behalf of
the Holders, except to the extent expressly provided in Article V hereof.

Section 7.14.     Tax Compliance.

         (a) The Agent, on its own behalf and on behalf of the Company, will
comply with all applicable certification, information reporting and withholding
(including "backup" withholding) requirements imposed by applicable tax laws,
regulations or administrative practice with respect to (i) any payments made
with respect to the Securities or (ii) the issuance, delivery, holding,
transfer, redemption or exercise of rights under the Securities. Such compliance
shall include, without limitation, the preparation and timely filing of required
returns and the timely payment of all amounts required to be withheld to the
appropriate taxing authority or its designated agent.

         (b) The Agent shall comply with any written direction received from the
Company with respect to the application of such requirements to particular
payments or Holders or in other particular circumstances, and may for purposes
of this


                                       70
<PAGE>   76

Agreement rely on any such direction in accordance with the provisions of
Section 7.1(a)(2) hereof.

         (c) The Agent shall maintain all appropriate records documenting
compliance with such requirements, and shall make such records available, on
written request, to the Company or its authorized representative within a
reasonable period of time after receipt of such request.


                                  ARTICLE VIII

                             Supplemental Agreements

Section 8.1.      Supplemental Agreements Without Consent of Holders.

         Without the consent of any Holders, the Company and the Agent, at any
time and from time to time, may enter into one or more agreements supplemental
hereto, in form satisfactory to the Company and the Agent, for any of the
following purposes:

                   (1) to evidence the succession of another Person to the
         Company, and the assumption by any such successor of the covenants of
         the Company herein and in the Certificates; or

                   (2) to add to the covenants of the Company for the benefit of
         the Holders, or to surrender any right or power herein conferred upon
         the Company; or

                   (3) to evidence and provide for the acceptance of appointment
         hereunder by a successor Agent; or

                   (4) to make provision with respect to the rights of Holders
         pursuant to the requirements of Section 5.6(c); or

                   (5) to cure any ambiguity, to correct or supplement any
         provisions herein which may be inconsistent with any other provisions
         herein, or to make any other provisions with respect to such matters or
         questions arising under this Agreement, provided such action shall not
         adversely affect the interests of the Holders.

                                       71
<PAGE>   77
Section 8.2.      Supplemental Agreements with Consent of Holders.

         With the consent of the Holders of not less than a majority of the
Outstanding Purchase Contracts voting together as one class, by Act of said
Holders delivered to the Company and the Agent, the Company, when authorized by
a Board Resolution, and the Agent may enter into an agreement or agreements
supplemental hereto for the purpose of modifying in any manner the terms of the
Purchase Contracts or the provisions of this Agreement or the rights of the
Holders in respect of the Securities (other than the Debentures, which may be
modified only in accordance with the applicable provisions of the Indenture;
provided, however, that, except as contemplated herein, no such supplemental
agreement shall, without the consent of the Holder of each Outstanding Security
affected thereby,

                  (1) change any Payment Date;

                  (2) change the amount or the type of Collateral required to be
         Pledged to secure a Holder's obligations under any Purchase Contract,
         impair the right of the Holder of any Purchase Contract to receive
         distributions on the related Collateral (except for the rights of
         Holders of Corporate Units to substitute the Treasury Securities for
         the pledged Debentures or the rights of holders of Treasury Units to
         substitute Debentures for the Pledged Treasury Securities) or otherwise
         adversely affect the Holder's rights in or to such Collateral or
         adversely alter the rights in or to such Collateral;

                  (3) impair the right to institute suit for the enforcement of
         any Purchase Contract;

                  (4) reduce the number of shares of Common Stock (or the amount
         of any other property) to be purchased pursuant to any Purchase
         Contract, increase the price to purchase shares of Common Stock (or any
         other property) upon settlement of any Purchase Contract, change the
         Purchase Contract Settlement Date or otherwise adversely affect the
         Holder's rights under any Purchase Contract; or

                  (5) reduce the percentage of the outstanding Purchase
         Contracts the consent of whose Holders is required for any such
         supplemental agreement;

provided, that if any amendment or proposal referred to above would adversely
affect only the Corporate Units or the Treasury Units, then only the affected
class of Holder


                                       72
<PAGE>   78

as of the record date for the Holders entitled to vote thereon will be entitled
to vote on such amendment or proposal, and such amendment or proposal shall not
be effective except with the consent of Holders of not less than a majority of
such class.

         It shall not be necessary for any Act of Holders under this Section to
approve the particular form of any proposed supplemental agreement, but it shall
be sufficient if such Act shall approve the substance thereof.

Section 8.3.      Execution of Supplemental Agreements.

         In executing, or accepting the additional agencies created by, any
supplemental agreement permitted by this Article or the modifications thereby
of the agencies created by this Agreement, the Agent shall be entitled to
receive and (subject to Section 7.1) shall be fully protected in relying upon,
an Opinion of Counsel stating that the execution of such supplemental agreement
is authorized or permitted by this Agreement. The Agent may, but shall not be
obligated to, enter into any such supplemental agreement which affects the
Agent's own rights, duties or immunities under this Agreement or otherwise.

Section 8.4.      Effect of Supplemental Agreements.

         Upon the execution of any supplemental agreement under this Article,
this Agreement and the Securities shall be modified in accordance therewith, and
such supplemental agreement shall form a part of this Agreement for all
purposes; and every Holder of Certificates theretofore or thereafter
authenticated, executed on behalf of the Holders and delivered hereunder shall
be bound thereby.

Section 8.5.      Reference to Supplemental Agreements.

         Certificates authenticated, executed on behalf of the Holders and
delivered after the execution of any supplemental agreement pursuant to this
Article may, and shall if required by the Agent, bear a notation in form
approved by the Agent as to any matter provided for in such supplemental
agreement. If the Company shall so determine, new Certificates so modified as to
conform, in the opinion of the Agent and the Company, to any such supplemental
agreement may be prepared and executed by the Company and authenticated,
executed on behalf of the Holders and delivered by the Agent in exchange for
Outstanding Certificates.


                                       73
<PAGE>   79
                                   ARTICLE IX

                    Consolidation, Merger, Sale or Conveyance

Section 9.1.      Covenant Not to Merge, Consolidate, Sell or Convey Property
                  Except Under Certain Conditions.

         The Company covenants that it will not merge or consolidate with any
other Person or sell, assign, transfer, lease or convey all or substantially all
of its properties and assets to any Person or group of affiliated Persons in one
transaction or a series of related transactions, unless (i) either the Company
shall be the continuing corporation, or the successor (if other than the
Company) shall be a corporation organized and existing under the laws of the
United States of America or a State thereof or the District of Columbia and such
corporation shall expressly assume all the obligations of the Company under the
Purchase Contracts, this Agreement, the Indenture, the Remarketing Agreement and
the Pledge Agreement by one or more supplemental agreements in form reasonably
satisfactory to the Agent and the Collateral Agent, executed and delivered to
the Agent and the Collateral Agent by such corporation, and (ii) the Company or
such successor corporation, as the case may be, shall not, immediately after
such merger or consolidation, or such sale, assignment, transfer, lease or
conveyance, be in default of its payment obligations under this Agreement or the
Debentures, or in default of its obligations to deliver Common Stock (or other
property) on the Purchase Contract Settlement Date or any Early Settlement Date,
or in material default in the performance of any other covenant hereunder or
under the Debentures, the Indenture, the Remarketing Agreement, the Purchase
Contracts or the Pledge Agreement.

Section 9.2.      Rights and Duties of Successor Corporation.

         In case of any such consolidation, merger, sale, assignment, transfer,
lease or conveyance and upon any such assumption by a successor corporation in
accordance with Section 9.1, such successor corporation shall succeed to and be
substituted for the Company with the same effect as if it had been named herein
as the Company, and its predecessor shall, except in the case of a lease, be
released from its obligations under this Agreement. Such successor corporation
thereupon may cause to be signed, and may issue either in its own name or in the
name of NRG Energy, Inc. any or all of the Certificates evidencing Securities
issuable hereunder which theretofore shall not have been signed by the Company
and delivered to the Agent; and, upon the order of such successor corporation,
instead of the Company, and subject to all the terms, conditions and limitations
in this Agreement prescribed, the


                                       74

<PAGE>   80
Agent shall authenticate and execute on behalf of the Holders and deliver any
Certificates which previously shall have been signed and delivered by the
officers of the Company to the Agent for authentication and execution, and any
Certificate evidencing Securities which such successor corporation thereafter
shall cause to be signed and delivered to the Agent for that purpose. All the
Certificates so issued shall in all respects have the same legal rank and
benefit under this Agreement as the Certificates theretofore or thereafter
issued in accordance with the terms of this Agreement as though all of such
Certificates had been issued at the date of the execution hereof.

         In case of any such consolidation, merger, sale, assignment, transfer,
lease or conveyance, such change in phraseology and form (but not in substance)
may be made in the Certificates evidencing Securities thereafter to be issued as
may be appropriate.

Section 9.3.      Opinion of Counsel Given to Agent.

         The Agent, subject to Sections 7.1 and 7.3, shall receive an Opinion of
Counsel as conclusive evidence that any such consolidation, merger, sale,
assignment, transfer, lease or conveyance, and any such assumption, complies
with the provisions of this Article and that all conditions precedent hereunder
to the consummation of any such consolidation, merger, sale, assignment,
transfer, lease or conveyance have been met.


                                    ARTICLE X

                                    Covenants

Section 10.1.     Performance Under Purchase Contracts.

         The Company covenants and agrees for the benefit of the Holders from
time to time of the Securities that it will duly and punctually perform its
obligations under the Purchase Contracts in accordance with the terms of the
Purchase Contracts and this Agreement.

Section 10.2.     Maintenance of Office or Agency.

         The Company will maintain or cause to be maintained in the Borough of
Manhattan, The City of New York an office or agency (a "New York Office")


                                       75

<PAGE>   81

Certificates may be presented or surrendered for payment and for acquisition of
shares of Common Stock (or other property) upon settlement of the Purchase
Contracts on the Purchase Contract Settlement Date or Early Settlement and for
transfer of Collateral upon occurrence of a Termination Event, where
Certificates may be surrendered for registration of transfer or exchange, for a
Collateral Substitution or re-establishment of a Corporate Unit and where
notices and demands to or upon the Company in respect of the Securities and this
Agreement may be served. The Company will give prompt written notice to the
Agent of the location, and any change in the location, of such office or agency.
If at any time the Company shall fail to maintain any such required office or
agency or shall fail to furnish the Agent with the address thereof, such
presentations, surrenders, notices and demands may be made or served at the
Corporate Trust Office, and the Company hereby appoints the Agent as its agent
to receive all such presentations, surrenders, notices and demands.

         The Company may also from time to time designate one or more other
offices or agencies where Certificates may be presented or surrendered for any
or all such purposes and may from time to time rescind such designations;
provided, however, that no such designation or rescission shall in any manner
relieve the Company of its obligation to maintain an office or agency in the
Borough of Manhattan, The City of New York for such purposes. The Company will
give prompt written notice to the Agent of any such designation or rescission
and of any change in the location of any such other office or agency.

         The Company hereby designates the Borough of Manhattan, the City of New
York, as the places of payment for the Securities, and hereby appoints the
Agent, acting through its Corporate Trust Office in ____________________, as the
registrar, paying agent and transfer agent for the Corporate Units and the
Treasury Units and for the other purposes contemplated by this Section 10.2.

Section 10.3.     Company to Reserve Common Stock.

         The Company shall at all times prior to the Purchase Contract
Settlement Date reserve and keep available, free from preemptive rights, out of
its authorized but unissued Common Stock the full number of shares of Common
Stock issuable against tender of payment in respect of all Purchase Contracts
constituting a part of the Securities evidenced by Outstanding Certificates.

Section 10.4.     Covenants as to Common Stock.


                                       76
<PAGE>   82

         The Company covenants that all shares of Common Stock which may be
issued against tender of payment in respect of any Purchase Contract
constituting a part of the Outstanding Securities will, upon issuance, be duly
authorized, validly issued, fully paid and nonassessable. The Company shall
comply with all applicable securities laws regulating the offer, issuance and
delivery of shares of Common Stock upon settlement of Purchase Contracts and
will endeavor to list such shares on each national securities exchange or
automated quotation system on which the Common Stock is then listed.


                                       77
<PAGE>   83

                  IN WITNESS WHEREOF, the parties hereto have caused this
Agreement to be duly executed as of the day and year first above written.

                                            NRG ENERGY, INC.


                                            By:____________________________
                                            Name:
                                            Title:



                                            By:____________________________
                                            Name:
                                            Title:


                                            _______________________________
                                            as Purchase Contract Agent


                                            By:____________________________
                                            Name:
                                            Title:



<PAGE>   84

                                    EXHIBIT A

                  (Form of Face of Corporate Units Certificate)

         THIS CERTIFICATE IS A GLOBAL CERTIFICATE WITHIN THE MEANING OF THE
PURCHASE CONTRACT AGREEMENT (AS HEREINAFTER DEFINED) AND IS REGISTERED IN THE
NAME OF THE CLEARING AGENCY OR A NOMINEE THEREOF. THIS CERTIFICATE MAY NOT BE
EXCHANGED IN WHOLE OR IN PART FOR A CERTIFICATE REGISTERED, AND NO TRANSFER OF
THIS CERTIFICATE IN WHOLE OR IN PART MAY BE REGISTERED, IN THE NAME OF ANY
PERSON OTHER THAN SUCH CLEARING AGENCY OR A NOMINEE THEREOF, EXCEPT IN THE
LIMITED CIRCUMSTANCES DESCRIBED IN THE PURCHASE CONTRACT AGREEMENT.

         UNLESS THIS CERTIFICATE IS PRESENTED BY AN AUTHORIZED REPRESENTATIVE OF
THE DEPOSITORY TRUST COMPANY (55 WATER STREET, NEW YORK, NEW YORK) TO THE
COMPANY OR ITS AGENT FOR REGISTRATION OF TRANSFER, EXCHANGE OR PAYMENT, AND ANY
CERTIFICATE ISSUED IS REGISTERED IN THE NAME OF CEDE & CO., OR SUCH OTHER NAME
AS REQUESTED BY AN AUTHORIZED REPRESENTATIVE OF THE DEPOSITORY TRUST COMPANY,
AND ANY PAYMENT HEREON IS MADE TO CEDE & CO., ANY TRANSFER, PLEDGE OR OTHER USE
HEREOF FOR VALUE OR OTHERWISE BY A PERSON IS WRONGFUL SINCE THE REGISTERED OWNER
HEREOF, CEDE & CO., HAS AN INTEREST HEREIN.

No. _____                                                            CUSIP No.
Number of Corporate Units _______


                              ____% Corporate Units

         This Corporate Units Certificate certifies that ___________ is the
registered Holder of the number of Corporate Units set forth above. Each
Corporate Unit represents (i) either (a) beneficial ownership by the Holder of
$25 principal amount of ____% Senior Debentures due _______________, 2006 (the
"Debenture"), subject to the Pledge of such Debenture by such Holder pursuant to
the Pledge Agreement or (b) upon the occurrence of a Tax Event Redemption prior
to the Purchase Contract Settlement Date or a Successful Initial Remarketing,
the

<PAGE>   85

appropriate Applicable Ownership Interest of the Treasury Portfolio, subject to
the Pledge of such Applicable Ownership Interest of the Treasury Portfolio by
such Holder pursuant to the Pledge Agreement, and (ii) the rights and
obligations of the Holder under one Purchase Contract with NRG Energy, Inc., a
Delaware corporation (the "Company," which term, as used herein, includes its
successors pursuant to the Purchase Contract Agreement). All capitalized terms
used herein which are defined in the Purchase Contract Agreement have the
meaning set forth therein.

         Pursuant to the Pledge Agreement, the Debentures or the appropriate
Applicable Ownership Interest of the Treasury Portfolio, as the case may be,
constituting part of each Corporate Unit evidenced hereby have been pledged to
the Collateral Agent, for the benefit of the Company, to secure the obligations
of the Holder under the Purchase Contract comprising a portion of such Corporate
Unit.

         The Pledge Agreement provides that all payments of principal on the
pledged Debentures or the appropriate Applicable Ownership Interest (as
specified in clause (A) of the definition of such term) of the Treasury
Portfolio, as the case may be, or interest payments on any pledged Debentures
(as defined in the Pledge Agreement) or the appropriate Applicable Ownership
Interest (as specified in clause (B) of the definition of such term) of the
Treasury Portfolio, as the case may be, constituting part of the Corporate Units
received by the Collateral Agent shall be paid by the Collateral Agent by wire
transfer in same day funds (i) in the case of (A) interest payments with respect
to pledged Debentures or the appropriate Applicable Owner ship Interest (as
specified in clause (B) of the definition of such term) of the Treasury
Portfolio, as the case may be, and (B) any payments of principal or the
appropriate Applicable Ownership Interest (as specified in clause (A) of the
definition of such terms) of the Treasury Portfolio, as the case may be, with
respect to any Debentures or the appropriate Applicable Ownership Interest of
the Treasury Portfolio, as the case may be, that have been released from the
Pledge pursuant to the Pledge Agreement, to the Agent to the account designated
by the Agent, no later than 2:00 p.m., New York City time, on the Business Day
such payment is received by the Collateral Agent (provided that in the event
such payment is received by the Collateral Agent on a day that is not a Business
Day or after 12:30 p.m., New York City time, on a Business Day, then such
payment shall be made no later than 10:30 a.m., New York City time, on the next
succeeding Business Day) and (ii) in the case of payments of principal on any
pledged Debentures or the appropriate Applicable Ownership Interest (as
specified in clause (A) of the definition of such term) of the Treasury
Portfolio that has not been released from the Pledge pursuant to the Pledge
Agreement, as the case may be, to the Company on the Purchase Contract
Settlement Date (as defined herein) in accordance with the terms of the Pledge
Agreement, in


                                      A-2
<PAGE>   86

full satisfaction of the respective obligations of the Holders of the Corporate
Units of which such pledged Debentures or the Treasury Portfolio, as the case
may be, are a part under the Purchase Contracts forming a part of such Corporate
Units. Interest on any Debentures or distributions on the appropriate Applicable
Ownership Interest (as specified in clause (B) of the definition of such term)
of the Treasury Portfolio, as the case may be, forming part of a Corporate Unit
evidenced hereby which are payable quarterly in arrears on _________, _________,
_________ and _________, each year, commencing _________, 2001 (a "Payment
Date"), shall, subject to receipt thereof by the Agent from the Collateral
Agent, be paid to the Person in whose name this Corporate Units Certificate (or
a Predecessor Corporate Units Certificate) is registered at the close of
business on the Record Date for such Payment Date.

         Each Purchase Contract evidenced hereby obligates the Holder of this
Corporate Units Certificate to purchase, and the Company to sell, on
_______________, 2004 (the "Purchase Contract Settlement Date"), at a price
equal to $25 (the "Stated Amount"), a number of newly issued shares of Common
Stock, $0.01 par value per share ("Common Stock"), of the Company equal to the
Settlement Rate, unless on or prior to the Purchase Contract Settlement Date
there shall have occurred a Termination Event or an Early Settlement with
respect to the Corporate Units of which such Purchase Contract is a part, all as
provided in the Purchase Contract Agreement and more fully described on the
reverse hereof. The purchase price (the "Purchase Price") for the shares of
Common Stock purchased pursuant to each Purchase Contract evidenced hereby, if
not paid earlier, shall be paid on the Purchase Contract Settlement Date by
application of payment received in respect of the Debentures or the appropriate
Applicable Ownership Interest (as specified in clause (A) of the definition of
such term) of the Treasury Portfolio, as the case may be, pledged to secure the
obligations under such Purchase Contract of the Holder of the Corporate Units of
which such Purchase Contract is a part.

         Interest on the Debentures or distributions on the appropriate
Applicable Ownership Interest (as specified in clause (B) of the definition of
such term) of the Treasury Portfolio, as the case may be, will be payable at the
Corporate Trust Office of the Agent and at the New York Office or, at the option
of the Company, by check mailed to the address of the Person entitled thereto as
such address appears on the Corporate Units Register.

         Reference is hereby made to the further provisions set forth on the
reverse hereof, which further provisions shall for all purposes have the same
effect as if set forth at this place.


                                      A-3
<PAGE>   87

         Unless the certificate of authentication hereon has been executed by
the Agent by manual signature, this Corporate Units Certificate shall not be
entitled to any benefit under the Pledge Agreement or the Purchase Contract
Agreement or be valid or obligatory for any purpose.









                                      A-4
<PAGE>   88



         IN WITNESS WHEREOF, the Company has caused this instrument to be duly
executed.

                                    NRG ENERGY, INC.


                                    By:_________________________________________
                                       Name:
                                       Title:


                                    By:_________________________________________
                                       Name:
                                       Title:


                                    HOLDER SPECIFIED ABOVE (as to
                                    obligations of such Holder under the
                                    Purchase Contracts evidenced hereby)

                                    By:________________________ not individually
                                       but solely as attorney-in-fact of such
                                       Holder


                                    By:_________________________________________
                                       Name:
                                       Title:
Dated:



<PAGE>   89
                      AGENT'S CERTIFICATE OF AUTHENTICATION

         This is one of the Corporate Units Certificates referred to in the
within mentioned Purchase Contract Agreement.

                                    By:___________________________________,
                                          as Purchase Contract Agent

                                    By:_________________________________________
                                              Authorized Signatory

Dated:


                                       A-6

<PAGE>   90
                (Form of Reverse of Corporate Units Certificate)


         Each Purchase Contract evidenced hereby is governed by a Purchase
Contract Agreement, dated as of _________, 2001 (as may be supplemented from
time to time, the "Purchase Contract Agreement"), between the Company and
______________________, as Purchase Contract Agent (including its successors
thereunder, herein called the "Agent"), to which Purchase Contract Agreement and
supplemental agreements thereto reference is hereby made for a description of
the respective rights, limitations of rights, obligations, duties and immunities
thereunder of the Agent, the Company and the Holders and of the terms upon which
the Corporate Units Certificates are, and are to be, executed and delivered.

         Each Purchase Contract evidenced hereby obligates the Holder of this
Corporate Units Certificate to purchase, and the Company to sell, on the
Purchase Contract Settlement Date at a price equal to the Purchase Price, a
number of newly issued shares of Common Stock of the Company equal to the
Settlement Rate, unless, on or prior to the Purchase Contract Settlement Date,
there shall have occurred a Termination Event or an Early Settlement with
respect to the Security of which such Purchase Contract is a part. The
"Settlement Rate" is equal to (a) if the Applicable Market Value (as defined
below) is equal to or greater than $______ (the "Threshold Appreciation Price"),
______ shares of Common Stock per Purchase Contract, (b) if the Applicable
Market Value is less than the Threshold Appreciation Price but is greater than
$_______, the number of shares of Common Stock per Purchase Contract equal to
the Stated Amount divided by the Applicable Market Value and (c) if the
Applicable Market Amount is less than or equal to $_______, _______ shares of
Common Stock per Purchase Contract, in each case subject to adjustment as
provided in the Purchase Contract Agreement. No fractional shares of Common
Stock will be issued upon settlement of Purchase Contracts, as provided in the
Purchase Contract Agreement.

         Each Purchase Contract evidenced hereby which is settled either through
Early Settlement or Cash Settlement shall obligate the Holder of the related
Corporate Units to purchase at the Purchase Price, and the Company to sell, a
number of newly issued shares of Common Stock equal to the Early Settlement Rate
or the Settlement Rate, as applicable.

         The "Applicable Market Value" means the average of the Closing Price
per share of Common Stock on each of the 20 consecutive Trading Days ending on
the third Trading Day immediately preceding the Purchase Contract Settlement
Date or,


                                       A-7

<PAGE>   91

for purposes of determining cash payable in lieu of factional shares in
connection with an Early Settlement, the third Trading Day immediately preceding
the relevant Early Settlement Date. The "Closing Price" of the Common Stock on
any date of determination means the closing sale price (or, if no closing price
is reported, the last reported sale price) of the Common Stock on The New York
Stock Exchange, Inc. (the "NYSE") on such date or, if the Common Stock is not
listed for trading on the NYSE on any such date, as reported in the composite
transactions for the principal United States securities exchange on which the
Common Stock is so listed, or if the Common Stock is not so listed on a United
States national or regional securities exchange, as reported by the Nasdaq
National Market, or, if the Common Stock is not so reported, the last quoted bid
price for the Common Stock in the over-the-counter market as reported by the
National Quotation Bureau or similar organization, or, if such bid price is not
available, the market value of the Common Stock on such date as determined by a
nationally recognized independent investment banking firm retained for this
purpose by the Company. A "Trading Day" means a day on which the Common Stock
(A) is not suspended from trading on any national or regional securities
exchange or association or over-the-counter market at the close of business and
(B) has traded at least once on the national or regional securities exchange or
association or over-the-counter market that is the primary market for the
trading of the Common Stock.

         In accordance with the terms of the Purchase Contract Agreement, the
Holder of this Corporate Units Certificate shall pay the Purchase Price for the
shares of Common Stock purchased pursuant to each Purchase Contract evidenced
hereby by effecting a Cash Settlement or an Early Settlement or from the
Proceeds of a remarketing of the related pledged Debentures of such holders.
Unless a Tax Event Redemption or a Successful Initial Remarketing has occurred,
a Holder of Corporate Units who does not elect to make an effective (1) Cash
Settlement on or prior to 5:00 p.m. New York City time on the fifth Business Day
immediately preceding the Purchase Contract Settlement Date, or (2) Early
Settlement on or prior to 5:00 p.m. New York City time on the fifth Business Day
immediately preceding the Purchase Contract Settlement Date, shall pay the
Purchase Price for the shares of Common Stock to be issued under the related
Purchase Contract from the Proceeds of the sale of the related pledged
Debentures held by the Collateral Agent. Unless a Tax Event Redemption or a
Successful Initial Remarketing has occurred, such sale will be made by the
Remarketing Agent pursuant to the terms of the Supplemental Remarketing
Agreement and the Remarketing Agreement on the third Business Day immediately
preceding the Purchase Contract Settlement Date. If a Tax Event Redemption or a
Successful Initial Remarketing has occurred, a Holder of Corporate Units who
does not elect to make an effective Early Settlement on or prior to 5:00 p.m.
New York


                                      A-8
<PAGE>   92

City time on the second Business Day immediately preceding the Purchase Contract
Settlement Date shall pay the Purchase Price with the Proceeds at maturity of
the Applicable Ownership Interest (as defined in clause (A) of the definition of
such term) of the Treasury Portfolio.

         The Company shall not be obligated to issue any shares of Common Stock
in respect of a Purchase Contract or deliver any certificates therefor to the
Holder unless it shall have received payment in full of the aggregate Purchase
Price for the shares of Common Stock to be purchased thereunder in the manner
herein set forth.

         Under the terms of the Pledge Agreement, the Agent will be entitled to
exercise the voting and any other consensual rights pertaining to the pledged
Debentures. Upon receipt of notice of any meeting at which holders of
Debentures are entitled to vote or upon the solicitation of consents, waivers or
proxies of holders of Debentures, the Agent shall, as soon as practicable
thereafter, mail to the Corporate Units holders a notice (a) containing such
information as is contained in the notice or solicitation, (b) stating that each
Corporate Units holder on the record date set by the Agent therefor (which, to
the extent possible, shall be the same date as the record date for determining
the holders of Debentures entitled to vote) shall be entitled to instruct the
Agent as to the exercise of the voting rights pertaining to the Debentures
constituting a part of such holder's Corporate Units and (c) stating the manner
in which such instructions may be given. Upon the written request of the
Corporate Units Holders on such record date, the Agent shall endeavor insofar as
practicable to vote or cause to be voted, in accordance with the instructions
set forth in such requests, the maximum number of Debentures as to which any
particular voting instructions are received. In the absence of specific
instructions from the Holder of a Corporate Unit, the Agent shall abstain from
voting the Debentures evidenced by such Corporate Units.

         Upon the occurrence of a Tax Event Redemption prior to the Purchase
Contract Settlement Date, pursuant to the terms of the Pledge Agreement, the
Collateral Agent will apply, out of the aggregate Redemption Price for the
Debentures that are components of Corporate Units, an amount equal to the
aggregate Redemption Amount for the Debentures that are components of Corporate
Units to purchase on behalf of the Holders of Corporate Units, the Treasury
Portfolio and, after deducting the Remarketing Fee to the extent permitted
under the terms of the Remarketing Agreement, promptly remit the remaining
portion of such Redemption Price to the Agent for payment to the Holders of such
Corporate Units.

                                      A-9
<PAGE>   93

         Upon the occurrence of a Successful Initial Remarketing, pursuant to
the terms of the Remarketing Agreement, the Remarketing Agent will apply an
amount equal to the Treasury Portfolio Purchase Price to purchase on behalf of
the Holders of Corporate Units, the Treasury Portfolio, and, after deducting the
Remarketing Fee to the extent permitted under the terms of the Remarketing
Agreement, promptly remit the remaining portion of such Proceeds of the
Successful Initial Remarketing to the Agent for payment to the Holders of such
Corporate Units.

         Following the occurrence of a Tax Event Redemption prior to the
Purchase Contract Settlement Date or a Successful Initial Remarketing, the
Holders of Corporate Units and the Collateral Agent shall have such security
interests rights and obligations with respect to the Treasury Portfolio as the
Holder of Corporate Units and the Collateral Agent had in respect of the
Debentures, as the case may be, subject to the Pledge thereof as provided in
Sections 2, 3, 4, 5 and 6 of the Pledge Agreement and any reference herein to
the Debenture shall be deemed to be a reference to such Treasury Portfolio and
any reference herein or in the Certificates to interest on the Debentures shall
be deemed to be a reference to corresponding distributions on the Treasury
Portfolio.

         The Corporate Units Certificates are issuable only in registered form
and only in denominations of a single Corporate Unit and any integral multiple
thereof. The transfer of any Corporate Units Certificate will be registered and
Corporate Units Certificates may be exchanged as provided in the Purchase
Contract Agreement. The Corporate Units Registrar may require a Holder, among
other things, to furnish appropriate endorsements and transfer documents
permitted by the Purchase Contract Agreement. No service charge shall be
required for any such registration of transfer or exchange, but the Company and
the Agent may require payment of a sum sufficient to cover any tax or other
governmental charge payable in connection therewith. A Holder who elects to
substitute Treasury Securities for Debentures or the appropriate Applicable
Ownership Interest of the Treasury Portfolio, thereby creating Treasury Units,
shall be responsible for any fees or expenses payable in connection therewith.
Except as provided in the Purchase Contract Agreement, for so long as the
Purchase Contract underlying a Corporate Unit remains in effect, such Corporate
Units shall not be separable into its constituent parts, and the rights and
obligations of the Holder of such Corporate Units in respect of Debentures or
the

                                      A-10

<PAGE>   94


appropriate Applicable Ownership Interest of the Treasury Portfolio, as the case
may be, and the Purchase Contract constituting such Corporate Units may be
transferred and ex changed only as a Corporate Unit. A Holder of a Corporate
Unit may create a Treasury Unit by delivering to the Collateral Agent Treasury
Securities in an aggregate principal amount equal to the aggregate principal
amount of the pledged Debentures or the appropriate Applicable Ownership
Interest (as specified in clause (A) of the definition of such term) of the
Treasury Portfolio, as the case may be, in exchange for the release of such
pledged Debentures or the appropriate Applicable Ownership Interest of the
Treasury Portfolio, as the case may be, in accordance with the terms of the
Purchase Contract Agreement and the Pledge Agreement. From and after such
Collateral Substitution, the Security for which such Pledged Treasury Securities
secures the Holder's obligation under the Purchase Contract shall be referred to
as a "Treasury Unit." A Holder may make such Collateral Substitution only in
integral multiples of 40 Corporate Units for 40 Treasury Units; provided,
however, that if a Tax Event Redemption or a Successful Initial Remarketing has
occurred and the Treasury Portfolio has become a component of the Corporate
Units, a Holder may make such Collateral Substitutions only in integral
multiples of ____ Corporate Units for ____ Treasury Units. Such Collateral
Substitution may cause the equivalent aggregate Stated Amount of this
Certificate to be increased or decreased; provided, however, the equivalent
aggregate Stated Amount outstanding under this Corporate Units Certificate shall
not exceed [$200,000,000]. All such adjustments to the equivalent aggregate
Stated Amount of this Corporate Units Certificate shall be duly recorded by
placing an appropriate notation on the Schedule attached hereto.

         A Holder of Treasury Units may recreate Corporate Units by delivering
to the Collateral Agent Debentures or the appropriate Applicable Ownership
Interest of the Treasury Portfolio, with an aggregate principal amount, in the
case of such Debentures, or with the appropriate Applicable Ownership Interest
(as specified in clause (A) of the definition of such term) of the Treasury
Portfolio, in the case of such appropriate Applicable Ownership Interest of the
Treasury Portfolio, equal to the aggregate principal amount of the Pledged
Treasury Securities in exchange for the release of such Pledged Treasury
Securities in accordance with the terms of the Purchase Contract Agreement and
the Pledge Agreement. Any such recreation of a Corporate Unit may be effected
only in multiples of 40 Treasury Units for 40 Corporate Units; provided,
however, that if a Tax Event Redemption or a Successful Initial Remarketing has
occurred and the Treasury Portfolio has become a component of the Corporate
Units, a Holder may make such substitution only in integral multiples of ____
Treasury Units for ____ Corporate Units.

         The Purchase Contracts and all obligations and rights of the Company
and the Holders thereunder, including, without limitation, the rights and
obligations of Holders to purchase Common Stock, shall immediately and
automatically terminate, without the necessity of any notice or action by any
Holder, the Agent or the Company, if, on or prior to the Purchase Contract
Settlement Date, a Termination Event shall have occurred. Upon the occurrence of
a Termination Event, the


                                      A-11
<PAGE>   95
Company shall promptly but in no event later than two Business Days thereafter
give written notice to the Agent, the Collateral Agent and to the Holders, at
their addresses as they appear in the Corporate Units Register. Upon and after
the occurrence of a Termination Event, the Collateral Agent shall release the
Debentures or the appropriate Applicable Ownership Interest of the Treasury
Portfolio, as the case may be, from the Pledge in accordance with the provisions
of the Pledge Agreement.

         Subject to and upon compliance with the provisions of the Purchase
Contract Agreement, at the option of the Holders thereof, Purchase Contracts
underlying Securities having an aggregate Stated Amount equal to $1,000 or an
integral multiple thereof may be settled early ("Early Settlement") as provided
in the Purchase Contract Agreement; provided, however, that if a Tax Event
Redemption or a Successful Initial Remarketing has occurred and the Treasury
Portfolio has become a component of the Corporate Units, Holders may early
settle Corporate Units only in integral multiples of ____ Corporate Units. In
order to exercise the right to effect Early Settlement with respect to any
Purchase Contracts evidenced by this Corporate Units Certificate, the Holder of
this Corporate Units Certificate shall deliver this Corporate Units Certificate
to the Agent at the Corporate Trust Office or the New York Office duly endorsed
for transfer to the Company or in blank with the form of Election to Settle
Early set forth below duly completed and accompanied by payment in the form of
immediately available funds payable to the Company in an amount (the "Early
Settlement Amount") equal to the product of (i) the Stated Amount times (ii) the
number of Purchase Contracts with respect to which the Holder has elected to
effect Early Settlement. Upon Early Settlement of Purchase Contracts by a Holder
of the related Securities, the pledged Debentures or the appropriate Applicable
Ownership Interest of the Treasury Portfolio underlying such Securities shall be
released from the Pledge as provided in the Pledge Agreement and the Holder
shall be entitled to receive a number of shares of Common Stock on account of
each Purchase Contract forming part of a Corporate Units as to which Early
Settlement is effected equal to the Early Settlement Rate. The Early Settlement
Rate shall initially be equal to __________ shares of Common Stock and shall be
adjusted in the same manner and at the same time as the Settlement Rate is
adjusted as provided in the Purchase Contract Agreement.

         Upon registration of transfer of this Corporate Units Certificate, the
transferee shall be bound (without the necessity of any other action on the part
of such transferee, except as may be required by the Agent pursuant to the
Purchase Contract Agreement) under the terms of the Purchase Contract Agreement,
the Pledge Agreement and the Purchase Contracts evidenced hereby and the
transferor shall be released from the obligations under the Purchase Contract
Agreement, the Pledge


                                      A-12
<PAGE>   96

Agreement and the Purchase Contracts evidenced by this Corporate Units
Certificate. The Company covenants and agrees, and the Holder, by its acceptance
hereof, likewise covenants and agrees, to be bound by the provisions of this
paragraph.

         The Holder of this Corporate Units Certificate, by its acceptance
hereof, authorizes the Agent to enter into and perform the related Purchase
Contracts forming part of the Corporate Units evidenced hereby on his behalf as
his attorney-in-fact, expressly withholds any consent to the assumption (i.e.,
affirmance) of the Purchase Contracts by the Company or its trustee in the event
that the Company becomes the subject of a case under the Bankruptcy Code, agrees
to be bound by the terms and provisions thereof, covenants and agrees to perform
its obligations under such Purchase Contracts, consents to the provisions of the
Purchase Contract Agreement, authorizes the Agent to enter into and perform the
Pledge Agreement on its behalf as its attorney-in-fact, and consents to the
Pledge of the Debentures or the appropriate Applicable Ownership Interest of the
Treasury Portfolio, as the case may be, underlying this Corporate Units
Certificate pursuant to the Pledge Agreement. The Holder further covenants and
agrees, that, to the extent and in the manner provided in the Purchase Contract
Agreement and the Pledge Agreement, but subject to the terms thereof, Proceeds
of the pledged Debentures or the appropriate Applicable Ownership Interest (as
specified in clause (A) of the definition of such term) of the Treasury
Portfolio on the Purchase Contract Settlement Date shall be paid by the
Collateral Agent to the Company in satisfaction of such Holder's obligations
under such Purchase Contract and such Holder shall acquire no right, title or
interest in such Proceeds.

         Subject to certain exceptions, the provisions of the Purchase Contract
Agreement may be amended with the consent of the Holders of a majority of the
Purchase Contracts.

         The Purchase Contracts shall for all purposes be governed by, and
construed in accordance with, the laws of the State of New York, without regard
to principles of conflicts of laws.

         The Company, the Agent and its Affiliates and any agent of the Company
or the Agent may treat the Person in whose name this Corporate Units Certificate
is registered as the owner of the Corporate Units evidenced hereby for the
purpose of receiving payments of interest payable quarterly on the Debentures or
on the maturing quarterly interest strips of the Treasury Portfolio, as
applicable, performance of the Purchase Contracts and for all other purposes
whatsoever, whether or not any payments in respect thereof be overdue and
notwithstanding any notice to the


                                      A-13
<PAGE>   97

contrary, and neither the Company, the Agent nor any such agent shall be
affected by notice to the contrary.

         The Purchase Contracts shall not, prior to the settlement thereof,
entitle the Holder to any of the rights of a holder of shares of Common Stock.

         A copy of the Purchase Contract Agreement is available for inspection
at the offices of the Agent.


                                      A-14

<PAGE>   98

                                  ABBREVIATIONS

         The following abbreviations, when used in the inscription on the face
of this instrument, shall be construed as though they were written out in full
according to applicable laws or regulations:

TEN COM  -                  as tenants in common

UNIF GIFT MIN ACT -         ------------Custodian------------
                            (cust)                   (minor)

                            Under Uniform Gifts to Minors Act

                            ------------------------------------
                                          (State)

TEN ENT -                   as tenants by the entireties

JT TEN -                    as joint tenants with right of survivorship and not
                            as tenants in common

Additional abbreviations may also be used though not in the above list.

                         ---------------------------------------------

         FOR VALUE RECEIVED, the undersigned hereby sell(s), assign(s) and
transfer(s) unto
                ----------------------------------------------------------------

--------------------------------------------------------------------------------
(Please insert Social Security or Taxpayer I.D. or other Identifying Number of
Assignee)

--------------------------------------------------------------------------------

--------------------------------------------------------------------------------

--------------------------------------------------------------------------------
(Please Print or Type Name and Address Including Postal Zip Code of Assignee)
the within Corporate Units Certificates and all rights thereunder, hereby
irrevocably constituting and appointing


--------------------------------------------------------------------------------
attorney to transfer said Corporate Units Certificates on the books of NRG
Energy, Inc. with full power of substitution in the premises.

Dated:
      -------------------               ----------------------------------------
                                        Signature

                                        NOTICE: The signature to this assignment
                                        must correspond with the name as it
                                        appears upon the face of the within
                                        Corporate Units Certificates in every
                                        particular, without alteration or
                                        enlargement or any change whatsoever.

Signature Guarantee:
                     --------------------------------------------------
Signatures must be guaranteed by an "eligible guarantor institution" meeting the
requirements of the Registrar, which requirements include membership or
participation in the Security Transfer Agent Medallion Program ("STAMP") or such
other "signature guarantee program" as may be determined by the Registrar in
addition to, or in substitution for, STAMP, all in accordance with the
Securities Exchange Act of 1934, as amended.

                                      A-15

<PAGE>   99

                             SETTLEMENT INSTRUCTIONS

         The undersigned Holder directs that a certificate for shares of Common
Stock deliverable upon settlement on or after the Purchase Contract Settlement
Date of the Purchase Contracts underlying the number of Corporate Units
evidenced by this Corporate Units Certificate be registered in the name of, and
delivered, together with a check in payment for any fractional share, to the
undersigned at the address indicated below unless a different name and address
have been indicated below. If shares are to be registered in the name of a
Person other than the undersigned, the undersigned will pay any transfer tax
payable incident thereto.

Dated:
      -------------------------------          ---------------------------------
                                                Signature
                                                Signature Guarantee:
                                                                    ------------
                                                (if assigned to another person)

         Signatures must be guaranteed by an "eligible guarantor institution"
meeting the requirements of the Registrar, which requirements include membership
or participation in the Security Transfer Agent Medallion Program ("STAMP") or
such other "signature guarantee program" as may be determined by the Registrar
in addition to, or in substitution for, STAMP, all in accordance with the
Securities Exchange Act of 1934, as amended.

If shares are to be registered in the name of and delivered to a Person other
than the Holder, please (i) print such Person's name and address REGISTERED
HOLDER and (ii) provide a guarantee of your signature: Please print name and
address of Registered Holder:

------------------------------------        ------------------------------------
                Name                                     Name
------------------------------------        ------------------------------------
               Address                                 Address
------------------------------------        ------------------------------------

------------------------------------        ------------------------------------

Social Security or other
Taxpayer Identification
Number, if any                         -----------------------------------------


                                      A-16
<PAGE>   100

                            ELECTION TO SETTLE EARLY

         The undersigned Holder of this Corporate Units Certificate hereby
irrevocably exercises the option to effect Early Settlement in accordance with
the terms of the Purchase Contract Agreement with respect to the Purchase
Contracts underlying the number of Corporate Units evidenced by this Corporate
Units Certificate specified below. The option to effect Early Settlement may be
exercised only with respect to Purchase Contracts underlying Corporate Units
with an aggregate Stated Amount equal to $1,000 or an integral multiple thereof;
provided, however, that if a Tax Event Redemption or a Successful Initial
Remarketing has occurred and the Treasury Portfolio has become a component of
the Corporate Units, Holders may early settle Corporate Units only in integral
multiples of __________ Corporate Units. The undersigned Holder directs that a
certificate for shares of Common Stock deliverable upon such Early Settlement be
registered in the name of, and delivered, together with a check in payment for
any fractional share and any Corporate Units Certificate representing any
Corporate Units evidenced hereby as to which Early Settlement of the related
Purchase Contracts is not effected, to the undersigned at the address indicated
below unless a different name and address have been indicated below. Pledged
Debentures or the appropriate Applicable Ownership Interest of the Treasury
Portfolio, as the case may be, deliverable upon such Early Settlement will be
transferred in accordance with the transfer instructions set forth below. If
shares are to be registered in the name of a Person other than the undersigned,
the undersigned will pay any transfer tax payable incident thereto.


Dated:______________________________      ______________________________________
                                                    Signature


Signature Guarantee
(if assigned to another person):______________________________________

Signatures must be guaranteed by an "eligible guarantor institution" meeting the
requirements of the Registrar, which requirements include membership or
participation in the Security Transfer Agent Medallion Program ("STAMP") or such
other "signature guarantee program" as may be determined by the Registrar in
addition to, or in substitution for, STAMP, all in accordance with the
Securities Exchange Act of 1934, as amended.


                                      A-17

<PAGE>   101

         Number of Securities evidenced hereby as to which Early Settlement of
the related Purchase Contracts is being elected:

If shares of Common Stock or Corporate Units Certificates are to be registered
in the name of and delivered to and pledged Debentures, or an Applicable
Ownership Interest in the Treasury Portfolio, as the case may be, are to be
transferred to a Person other than the Holder, please (i) print such Person's
name and address and (ii) provide a guarantee of your signature:




------------------------------------
            Name

------------------------------------
           Address

------------------------------------


------------------------------------


------------------------------------


------------------------------------


REGISTERED HOLDER

Please print name and address of Registered Holder:


------------------------------------
               Name

------------------------------------
             Address

------------------------------------


------------------------------------


------------------------------------


------------------------------------

Social Security or other
Taxpayer Identification
Number, if any
                                            ------------------------------------


                                      A-18

<PAGE>   102

Transfer Instructions for pledged Debentures, or the Applicable Ownership
Interest in the Treasury Portfolio, as the case may be, Transferable Upon Early
Settlement or a Termination Event:


--------------------------------------------------------------------------------

--------------------------------------------------------------------------------

--------------------------------------------------------------------------------

--------------------------------------------------------------------------------


                                      A-19

<PAGE>   103
                     [TO BE ATTACHED TO GLOBAL CERTIFICATES]

            SCHEDULE OF INCREASES OR DECREASES IN GLOBAL CERTIFICATE

                  The following increases or decreases in this Global
Certificate have been made:

<TABLE>
<CAPTION>

                              Amount of               Amount of        Stated Amount of this   Signature of authorized
                          decrease in Stated      increase in Stated     Global Certificate    signatory of Purchase
                         Amount of the Global    Amount of the Global  following such decrease  Contract Agent or
         Date                Certificate             Certificate            or increase         Securities Custodian

<S>                   <C>                      <C>                     <C>                     <C>
----------------------------------------------------------------------------------------------------------------------


----------------------------------------------------------------------------------------------------------------------


----------------------------------------------------------------------------------------------------------------------


----------------------------------------------------------------------------------------------------------------------


----------------------------------------------------------------------------------------------------------------------


----------------------------------------------------------------------------------------------------------------------


======================================================================================================================
</TABLE>


                                      A-20

<PAGE>   104
                                    EXHIBIT B

                  (Form of Face of Treasury Units Certificate)

         THIS CERTIFICATE IS A GLOBAL CERTIFICATE WITHIN THE MEANING OF THE
PURCHASE CONTRACT AGREEMENT (AS HEREINAFTER DEFINED) AND IS REGISTERED IN THE
NAME OF THE CLEARING AGENCY OR A NOMINEE THEREOF. THIS CERTIFICATE MAY NOT BE
EXCHANGED IN WHOLE OR IN PART FOR A CERTIFICATE REGISTERED, AND NO TRANSFER OF
THIS CERTIFICATE IN WHOLE OR IN PART MAY BE REGISTERED, IN THE NAME OF ANY
PERSON OTHER THAN SUCH CLEARING AGENCY OR A NOMINEE THEREOF, EXCEPT IN THE
LIMITED CIRCUMSTANCES DESCRIBED IN THE PURCHASE CONTRACT AGREEMENT.

         UNLESS THIS CERTIFICATE IS PRESENTED BY AN AUTHORIZED REPRESENTATIVE OF
THE DEPOSITORY TRUST COMPANY (55 WATER STREET, NEW YORK, NEW YORK) TO THE
COMPANY OR ITS AGENT FOR REGISTRATION OF TRANSFER, EXCHANGE OR PAYMENT AND ANY
CERTIFICATE ISSUED IS REGISTERED IN THE NAME OF CEDE & CO., OR SUCH OTHER NAME
AS REQUESTED BY AN AUTHORIZED REPRESENTATIVE OF THE DEPOSITORY TRUST COMPANY,
AND ANY PAYMENT HEREON IS MADE TO CEDE & CO., ANY TRANSFER, PLEDGE OR OTHER USE
HEREOF FOR VALUE OR OTHERWISE BY A PERSON IS WRONGFUL SINCE THE REGISTERED OWNER
HEREOF, CEDE & CO., HAS AN INTEREST HEREIN.

No._______________                                                   CUSIP NO.

Number of Treasury Units ________________

                              ____ % Treasury Units


         This Treasury Units Certificate certifies that __________ is the
registered Holder of the number of Treasury Units set forth above. Each Treasury
Units represents (i) a 1/40, or 2.5%, undivided beneficial ownership interest
in a Treasury Security having a principal amount at maturity equal to $1,000,
subject to the Pledge of such Treasury Security by such Holder pursuant to the
Pledge Agreement, and (ii) the rights and obligations of the Holder under one
Purchase Contract with NRG

<PAGE>   105


Energy, Inc., a Delaware corporation (the "Company," which term, as used herein,
includes its successors pursuant to the Purchase Contract Agreement). All
capitalized terms used herein which are defined in the Purchase Contract
Agreement have the meaning set forth therein.

         Pursuant to the Pledge Agreement, the Treasury Securities constituting
part of each Treasury Units evidenced hereby have been pledged to the Collateral
Agent, for the benefit of the Company, to secure the obligations of the Holder
under the Purchase Contract comprising a portion of such Treasury Units.

         The Pledge Agreement provides that all payments of the principal of any
Treasury Securities received by the Collateral Agent shall be paid by the
Collateral Agent by wire transfer of same day funds (i) in the case of any
principal payments with respect to any Treasury Securities that have been
released from the Pledge pursuant to the Pledge Agreement, to the Holders of the
applicable Treasury Units to the accounts designated by them in writing for such
purpose no later than 2:00 p.m. New York City time, on the Business Day such
payment is received by the Collateral Agent (provided that in the event such
payment is received by the Collateral Agent on a day that is not a Business Day
or after 12:30 p.m., New York City time, on a Business Day, then such payment
shall be made no later than 10:30 a.m., New York City time, on the next
succeeding Business Day), and (ii) in the case of the principal of any Pledged
Treasury Securities, to the Company on the Purchase Contract Settlement Date (as
defined herein) in accordance with the terms of the Pledge Agreement, in full
satisfaction of the respective obligations of the Holders of the Treasury Units
of which such Pledged Treasury Securities are a part under the Purchase
Contracts forming a part of such Treasury Units.

         Each Purchase Contract evidenced hereby obligates the Holder of this
Treasury Units Certificate to purchase, and the Company to sell, on ___________,
2004 (the "Purchase Contract Settlement Date"), at a price equal to $25 (the
"Stated Amount"), a number of newly issued shares of Common stock, $0.01 par
value per share ("Common Stock"), of the Company equal to the Settlement Rate,
unless on or prior to the Purchase Contract Settlement Date there shall have
occurred a Termination Event or an Early Settlement with respect to the
Treasury Units of which such Purchase Contract is a part, all as provided in the
Purchase Contract Agreement and more fully described on the reverse hereof. The
purchase price (the "Purchase Price") for the shares of Common Stock purchased
pursuant to each Purchase Contract evidenced hereby, if not paid earlier, shall
be paid on the Purchase Contract Settlement Date by application of the Proceeds
from the Treasury Securities

                                       B-2

<PAGE>   106

pledged to secure the obligations under such Purchase Contract in accordance
with the terms of the Pledge Agreement.

         Reference is hereby made to the further provisions set forth on the
reverse hereof, which further provisions shall for all purposes have the same
effect as if set forth at this place.

         Unless the certificate of authentication hereon has been executed by
the Agent by manual signature, this Treasury Units Certificate shall not be
entitled to any benefit under the Pledge Agreement or the Purchase Contract
Agreement or be valid or obligatory for any purpose.

                                       B-3

<PAGE>   107

         IN WITNESS WHEREOF, the Company has caused this instrument to be duly
executed.

                                   NRG ENERGY, INC.


                                   By:________________________________________
                                   Name:
                                   Title:

                                   By:________________________________________
                                   Name:
                                   Title:

                                   HOLDER SPECIFIED ABOVE (as to
                                   obligations of such Holder under the
                                   Purchase Contracts)

                                   By:   THE BANK OF NEW YORK not individually
                                         but solely as attorney-in-fact
                                         of such Holder

                                   By:________________________________________
                                   Name:
                                   Title:
Dated:

                      AGENT'S CERTIFICATE OF AUTHENTICATION

         This is one of the Treasury Units referred to in the within-mentioned
Purchase Contract Agreement.

                                   By:   THE BANK OF NEW YORK,
                                          as Purchase Contract Agent

                                   By:________________________________________
                                         Authorized Signatory

<PAGE>   108



                              (Form of Reverse of
                           Treasury Units Certificate)

         Each Purchase Contract evidenced hereby is governed by a Purchase
Contract Agreement, dated as of _________, 2001 (as may be supplemented from
time to time, the "Purchase Contract Agreement"), between the Company and
_____________, as Purchase Contract Agent (including its successors thereunder,
herein called the "Agent"), to which the Purchase Contract Agreement and
supplemental agreements thereto reference is hereby made for a description of
the respective rights, limitations of rights, obligations, duties and immunities
thereunder of the Agent, the Company and the Holders and of the terms upon which
the Treasury Units Certificates are, and are to be, executed and delivered.

         Each Purchase Contract evidenced hereby obligates the Holder of this
Treasury Units Certificate to purchase, and the Company to sell, on the Purchase
Contract Settlement Date at the Purchase Price, a number of newly issued shares
of Common Stock of the Company equal to the Settlement Rate, unless, on or prior
to the Purchase Contract Settlement Date, there shall have occurred a
Termination Event or an Early Settlement with respect to the Security of which
such Purchase Contract is a part. The "Settlement Rate" is equal to (a) if the
Applicable Market Value (as defined below) is equal to or greater than $______
(the "Threshold Appreciation Price"), _______ shares of Common Stock per
Purchase Contract, (b) if the Applicable Market Value is less than the
Threshold Appreciation Price but is greater than $______, the number of shares
of Common Stock per Purchase Contract equal to the Stated Amount divided by the
Applicable Market Value and (c) if the Applicable Market Amount is less than or
equal to $______, ______ shares of Common Stock per Purchase Contract, in each
case subject to adjustment as provided in the Purchase Contract Agreement. No
fractional shares of Common Stock will be issued upon settlement of Purchase
Contracts, as provided in the Purchase Contract Agreement.

         Each Purchase Contract evidenced hereby which is settled through Early
Settlement shall obligate the Holder of the related Treasury Units to purchase
at the Purchase Price, and the Company to sell, a number of newly issued shares
of Common Stock equal to the Early Settlement Rate.

         The "Applicable Market Value" means the average of the Closing Price
per share of Common Stock on each of the 20 consecutive Trading Days ending on
the third Trading Day immediately preceding the Purchase Contract Settlement
Date or, for purposes of determining cash payable in lieu of fractional shares
in connection with an Early Settlement, the third Trading Day immediately
preceding the relevant Early Settlement Date. The "Closing Price" of the Common
Stock on any date of determination means the closing sale price (or, if no
closing price is reported, the last

<PAGE>   109

reported sale price) of the Common Stock on The New York Stock Exchange, Inc.
(the "NYSE") on such date or, if the Common Stock is not listed for trading on
the NYSE on any such date, as reported in the composite transactions for the
principal United States securities exchange on which the Common Stock is so
listed, or if the Common Stock is not so listed on a United States national or
regional securities exchange, as reported by the Nasdaq National Market or, if
the Common Stock is not so reported, the last quoted bid price for the Common
Stock in the over-the-counter market as reported by the National Quotation
Bureau or similar organization, or, if such bid price is not available, the
market value of the Common Stock on such date as determined by a nationally
recognized independent investment banking firm retained for this purpose by the
Company. A "Trading Day" means a day on which the Common Stock (A) is not
suspended from trading on any national or regional securities exchange or
association or over-the-counter market at the close of business and (B) has
traded at least once on the national or regional securities exchange or
association or over-the-counter market that is the primary market for the
trading of the Common Stock.

         In accordance with the terms of the Purchase Contract Agreement, the
Holder of this Treasury Units Certificate shall pay the Purchase Price for the
shares of Common Stock purchased pursuant to each Purchase Contract evidenced
hereby by effecting either an Early Settlement of each such Purchase Contract or
by applying a principal amount of the Pledged Treasury Securities underlying
such Holder's Treasury Units equal to the Stated Amount to the purchase of the
Common Stock. A Holder of Treasury Units who does not elect, on or prior to 5:00
p.m. New York City time on the second Business Day immediately preceding the
Purchase Contract Settlement Date, to make an Early Settlement, shall pay the
Purchase Price for the shares of Common Stock to be issued on the related
Purchase Contract by applying a principal amount of the Pledged Treasury
Securities as aforesaid.

         The Company shall not be obligated to issue any shares of Common Stock
in respect of a Purchase Contract or deliver any certificates therefor to the
Holder unless it shall have received payment in full of the aggregate Purchase
Price for the shares of Common Stock to be purchased thereunder in the manner
herein set forth.

         The Treasury Units Certificates are issuable only in registered form
and only in denominations of a single Treasury Units and any integral multiple
thereof. The transfer of any Treasury Units Certificate will be registered and
Treasury Units Certificates may be exchanged as provided in the Purchase
Contract Agreement. The Treasury Units Registrar may require a Holder, among
other things, to furnish appropriate endorsements and transfer documents
permitted by the Purchase Contract Agreement. No service charge shall be
required for any such registration of transfer or exchange, but the Company and
the Agent may require payment of a sum sufficient

                                       B-6



<PAGE>   110

to cover any tax or other governmental charge payable in connection
therewith. A Holder who elects to substitute Debentures or the appropriate
Applicable Owner ship Interest of the Treasury Portfolio, as the case may be,
for Treasury Securities, thereby recreating Corporate Units, shall be
responsible for any fees or expenses payable in connection therewith. Except as
provided in the Purchase Contract Agreement, for so long as the Purchase
Contract underlying a Treasury Units remains in effect, such Treasury Units
shall not be separable into its constituent parts, and the rights and
obligations of the Holder of such Treasury Units in respect of the Treasury
Security and the Purchase Contract constituting such Treasury Units may be
transferred and exchanged only as a Treasury Units. A Holder of Treasury Units
may recreate Corporate Units by delivering to the Collateral Agent Debentures or
the appropriate Applicable Ownership Interest of the Treasury Portfolio, with an
aggregate principal amount, in the case of such Debentures, or with the
appropriate Applicable Ownership Interest (as specified in clause (A) of the
definition of such term) of the Treasury Portfolio, in the case of such
appropriate Applicable Ownership Interest of the Treasury Portfolio, equal to
the aggregate principal amount of the pledged Treasury Securities in exchange
for the release of such pledged Treasury Securities in accordance with the terms
of the Purchase Contract Agreement and the Pledge Agreement. From and after such
substitution, the Security for which such pledged Debentures or appropriate
Applicable Ownership Interest of the Treasury Portfolio, as the case may be,
secures the Holder's obligation under the Purchase Contract shall be referred to
as a "Corporate Units." A Holder may make such a substitution only in integral
multiples of 40 Treasury Units for 40 Corporate Units; provided, however, that
if a Tax Event Redemption or a Successful Initial Remarketing has occurred and
the Treasury Portfolio has become a component of the Corporate Units, a Holder
may make such substitution only in integral multiples of _____ Treasury Units
for ______ Corporate Units. Such substitution may cause the equivalent aggregate
Stated Amount of this Certificate to be increased or decreased; provided,
however, the equivalent aggregate Stated Amount outstanding under this Treasury
Units Certificate shall not exceed $[200,000,000]. All such adjustments to the
equivalent aggregate Stated Amount of this Treasury Units Certificate shall be
duly recorded by placing an appropriate notation on the Schedule attached
hereto.

         A Holder of a Corporate Unit may create a Treasury Unit by delivering
to the Collateral Agent Treasury Securities in an aggregate principal amount of
the pledged Debentures or the appropriate Applicable Ownership Interest (as
specified in clause (A) of the definition of such term) of the Treasury
Portfolio, as the case may be, in exchange for the release of such pledged
Debentures or the appropriate Applicable Ownership Interest of the Treasury
Portfolio, as the case may be, in accordance with the terms of the Purchase
Contract Agreement and the Pledge Agreement. Any such creation of a Treasury
Units may be effected only in multiples of 40 Corporate Units for 40 Treasury
Units; provided, however, if a Tax Event Redemption or a Successful

                                      B-7
<PAGE>   111
Initial Remarketing has occurred and the Treasury Portfolio has become a
component of the Corporate Unit, a Holder may make such Collateral Substitution
only in integral multiples of __ Corporate Units for __ Treasury Units.

         The Purchase Contracts and all obligations and rights of the Company
and the Holders thereunder, including, without limitation, the rights and
obligations of Holders to purchase Common Stock shall immediately and
automatically terminate, without the necessity of any notice or action by any
Holder, the Agent or the Company, if, on or prior to the Purchase Contract
Settlement Date, a Termination Event shall have occurred. Upon the occurrence of
a Termination Event, the Company shall promptly but in no event later than two
Business Days thereafter give written notice to the Agent, the Collateral Agent
and to the Holders, at their addresses as they appear in the Treasury Units
Register. Upon and after the occurrence of a Termination Event, the Collateral
Agent shall release the Treasury Securities from the Pledge in accordance with
the provisions of the Pledge Agreement.

         Subject to and upon compliance with the provisions of the Purchase
Contract Agreement, at the option of the Holders thereof, Purchase Contracts
underlying Securities having an aggregate Stated Amount equal to $1,000 or an
integral multiple thereof may be settled early ("Early Settlement") as provided
in the Purchase Contract Agreement. In order to exercise the right to effect
Early Settlement with respect to any Purchase Contracts evidenced by this
Treasury Units Certificate, the Holder of this Treasury Units Certificate shall
deliver this Treasury Units Certificate to the Agent at the Corporate Trust
Office or the New York Office duly endorsed for transfer to the Company or in
blank with the form of Election to Settle Early set forth below duly completed
and accompanied by payment in the form of immediately available funds payable to
the Company in an amount (the "Early Settlement Amount") equal to the product of
(i) the Stated Amount times (ii) the number of Purchase Contracts with respect
to which the Holder has elected to effect Early Settlement. Upon Early
Settlement of Purchase Contracts by a Holder of the related Securities, the
Pledged Treasury Securities underlying such Securities shall be released from
the Pledge as provided in the Pledge Agreement and the Holder shall be entitled
to receive a number of shares of Common Stock on account of each Purchase
Contract forming part of a Treasury Units as to which Early Settlement is
effected equal to the Early Settlement Rate. The Early Settlement Rate shall
initially be equal to _______ shares of Common Stock and shall be adjusted in
the same manner and at the same time as the Settlement Rate is adjusted as
provided in the Purchase Contract Agreement.

         Upon registration of transfer of this Treasury Units Certificate, the
transferee shall be bound (without the necessity of any other action on the part
of such transferee, except as may be required by the Agent pursuant to the
Purchase Contract


                                      B-8


<PAGE>   112
Agreement) under the terms of the Purchase Contract Agreement, the Pledge
Agreement and the Purchase Contracts evidenced hereby and the transferor shall
be released from the obligations under the Purchase Contract Agreement, the
Pledge Agreement and the Purchase Contracts evidenced by this Treasury Units
Certificate. The Company covenants and agrees, and the Holder, by his acceptance
hereof, likewise covenants and agrees, to be bound by the provisions of this
paragraph.

         The Holder of this Treasury Units Certificate, by its acceptance
hereof, authorizes the Agent to enter into and perform the related Purchase
Contracts forming part of the Treasury Units evidenced hereby on his behalf as
its attorney-in-fact, expressly withholds any consent to the assumption (i.e.,
affirmance) of the Purchase Contracts by the Company or its trustee in the event
that the Company becomes the subject of a case under the Bankruptcy Code, agrees
to be bound by the terms and provisions thereof, covenants and agrees to perform
its obligations under such Purchase Contracts, consents to the provisions of the
Purchase Contract Agreement, authorizes the Agent to enter into and perform the
Pledge Agreement on its behalf as its attorney-in-fact, and consents to the
Pledge of the Treasury Securities underlying this Treasury Units Certificate
pursuant to the Pledge Agreement. The Holder further covenants and agrees, that,
to the extent and in the manner provided in the Purchase Contract Agreement and
the Pledge Agreement, but subject to the terms thereof, Proceeds of the pledged
Treasury Securities on the Purchase Contract Settlement Date shall be paid by
the Collateral Agent to the Company in satisfaction of such Holder's obligations
under such Purchase Contract and such Holder shall acquire no right, title or
interest in such Proceeds.

         Subject to certain exceptions, the provisions of the Purchase Contract
Agreement may be amended with the consent of the Holders of a majority of the
Purchase Contracts.

         The Purchase Contracts shall for all purposes be governed by, and
construed in accordance with, the laws of the State of New York, without regard
to principles of conflicts of laws.

         The Company, the Agent and its Affiliates and any agent of the Company
or the Agent may treat the Person in whose name this Treasury Units Certificate
is registered as the owner of the Treasury Units evidenced hereby for the
purpose of receiving payments on the Treasury Securities and performance of the
Purchase Contracts and for all other purposes whatsoever, whether or not any
payments in respect thereof be overdue and notwithstanding any notice to the
contrary, and neither the Company, the Agent nor any such agent shall be
affected by notice to the contrary.

                                      B-9

<PAGE>   113

         The Purchase Contracts shall not, prior to the settlement thereof,
entitle the Holder to any of the rights of a holder of shares of Common Stock.

         A copy of the Purchase Contract Agreement is available for inspection
at the offices of the Agent.

                                      B-10

<PAGE>   114



                                  ABBREVIATIONS

         The following abbreviations, when used in the inscription on the face
of this instrument, shall be construed as though they were written out in full
according to applicable laws or regulations:

TEN COM  -              as tenants in common

UNIF GIFT MIN ACT -     ____________Custodian____________
                        (cust)                   (minor)

                        Under Uniform Gifts to Minors Act

                        _________________________________
                                     (State)

TEN ENT -               as tenants by the entireties

JT TEN -                as joint tenants with right of survivorship and not as
                        tenants in common

Additional abbreviations may also be used though not in the above list.

                        ________________________________


          FOR VALUE RECEIVED, the undersigned hereby sell(s), assign(s) and
transfer(s) unto_______________________________________________________________
_______________________________________________________________________________
(Please insert Social Security or Taxpayer I.D. or other Identifying Number of
Assignee) _____________________________________________________________________
_______________________________________________________________________________
_______________________________________________________________________________

(Please Print or Type Name and Address Including Postal Zip Code of Assignee)
the within Treasury Units Certificates and all rights thereunder, hereby
irrevocably constituting and appointing
_______________________________________________________________________________
attorney to transfer said Treasury Units Certificates on the books of NRG
Energy, Inc. with full power of substitution in the premises.

Dated:  _________________
                                              _________________________________
                                              Signature

                                              NOTICE: The signature to
                                              this assignment must
                                              correspond with the name as
                                              it appears upon the face of
                                              the within Treasury Units
                                              Certificates in every
                                              particular, without
                                              alteration or enlargement
                                              or any change whatsoever.

Signature Guarantee:___________________________________________________________
Signatures must be guaranteed by an "eligible guarantor institution" meeting the
requirements of the Registrar, which requirements include membership or
participation in the Security Transfer Agent Medallion Program ("STAMP") or such
other "signature guarantee program" as may be determined by the Registrar in
addition to, or in substitution for, STAMP, all in accordance with the
Securities Exchange Act of 1934, as amended.

                                      B-11

<PAGE>   115



                             SETTLEMENT INSTRUCTIONS

         The undersigned Holder directs that a certificate for shares of Common
Stock deliverable upon settlement on or after the Purchase Contract Settlement
Date of the Purchase Contracts underlying the number of Treasury Units evidenced
by this Treasury Units Certificate be registered in the name of, and delivered,
together with a check in payment for any fractional share, to the undersigned at
the address indicated below unless a different name and address have been
indicated below. If shares are to be registered in the name of a Person other
than the undersigned, the undersigned will pay any transfer tax payable incident
thereto.

Dated:                                         Signature
      ---------------------------------        --------------------------------
                                               Signature Guarantee:
                                                                   ------------
                                               (if assigned to another person)

         Signatures must be guaranteed by an "eligible guarantor institution"
meeting the requirements of the Registrar, which requirements include membership
or participation in the Security Transfer Agent Medallion Program ("STAMP") or
such other "signature guarantee program" as may be determined by the Registrar
in addition to, or in substitution for, STAMP, all in accordance with the
Securities Exchange Act of 1934, as amended.

If shares are to be registered in the name of and delivered to a Person other
than the Holder, please (i) print such Person's name and address and (ii)
provide a guarantee of your signature:


 -------------------------------------------------------------------------------
                                      Name

 -------------------------------------------------------------------------------
                                     Address

 -------------------------------------------------------------------------------

 -------------------------------------------------------------------------------

 -------------------------------------------------------------------------------

Social Security or other
Taxpayer Identification
Number, if any
              ------------------------------------------------------------------

REGISTERED HOLDER

Please print name and address of Registered Holder:


 -------------------------------------------------------------------------------
                                      Name

 -------------------------------------------------------------------------------
                                     Address

 -------------------------------------------------------------------------------

 -------------------------------------------------------------------------------

 -------------------------------------------------------------------------------


                                      B-12

<PAGE>   116



                            ELECTION TO SETTLE EARLY


         The undersigned Holder of this Treasury Units Certificate hereby
irrevocably exercises the option to effect Early Settlement in accordance with
the terms of the Purchase Contract Agreement with respect to the Purchase
Contracts underlying the number of Treasury Units evidenced by this Treasury
Units Certificate specified below. The option to effect Early Settlement may be
exercised only with respect to Purchase Contracts underlying Treasury Units with
an aggregate Stated Amount equal to $1,000 or an integral multiple thereof. The
undersigned Holder directs that a certificate for shares of Common Stock
deliverable upon such Early Settlement be registered in the name of, and
delivered, together with a check in payment for any fractional share and any
Treasury Units Certificate representing any Treasury Units evidenced hereby as
to which Early Settlement of the related Purchase Contracts is not effected, to
the undersigned at the address indicated below unless a different name and
address have been indicated below. Pledged Treasury Securities deliverable upon
such Early Settlement will be transferred in accordance with the transfer
instructions set forth below. If shares are to be registered in the name of a
Person other than the undersigned, the undersigned will pay any transfer or
similar tax payable incident thereto.

Dated:________________             ____________________________________________
                                   Signature


Signature Guarantee: ____________________________________
(if assigned to another person)

Signatures must be guaranteed by an "eligible guarantor institution" meeting the
requirements of the Registrar, which requirements include membership or
participation in the Security Transfer Agent Medallion Program ("STAMP") or such
other "signature guarantee program" as may be determined by the Registrar in
addition to, or in substitution for, STAMP, all in accordance with the
Securities Exchange Act of 1934, as amended.


                                      B-13
<PAGE>   117



         Number of Securities evidenced hereby as to which Early Settlement of
the related Purchase Contracts is being elected:

If shares of Common Stock or Treasury Units Certificates are to be registered
in the name of and delivered to and pledged Treasury Securities are to be
transferred to a Person other than the Holder, please (i) print such Person's
name and address and (ii) provide a guarantee of your signature:

--------------------------------------------------------------------------------
                                      Name

--------------------------------------------------------------------------------
                                     Address

--------------------------------------------------------------------------------

--------------------------------------------------------------------------------

--------------------------------------------------------------------------------


Social Security or other
Taxpayer Identification
Number, if any
               ----------------------------------

Please print name and address of Registered Holder:

--------------------------------------------------------------------------------
                                      Name

--------------------------------------------------------------------------------
                                     Address

--------------------------------------------------------------------------------

--------------------------------------------------------------------------------

--------------------------------------------------------------------------------

Transfer Instructions for pledged Treasury Securities Transferable Upon Early
Settlement or a Termination Event:

--------------------------------------------------------------------------------

--------------------------------------------------------------------------------

--------------------------------------------------------------------------------

                                      B-14

<PAGE>   118



                     [TO BE ATTACHED TO GLOBAL CERTIFICATES]

            SCHEDULE OF INCREASES OR DECREASES IN GLOBAL CERTIFICATE

              The following increases or decreases in this Global
                          Certificate have been made:


<TABLE>
<CAPTION>
                                                                           Stated Amount of this       Signature of
                                Amount of               Amount of           Global Certificate    authorized signatory of
                           decrease in Stated       increase in Stated        following such        Purchase Contract
                          Amount of the Global     Amount of the Global        decrease or          Agent or Securities
         Date                  Certificate             Certificate              increase                Custodian
--------------------------------------------------------------------------------------------------------------------------
<S>                       <C>                      <C>                     <C>                    <C>

--------------------------------------------------------------------------------------------------------------------------

--------------------------------------------------------------------------------------------------------------------------

--------------------------------------------------------------------------------------------------------------------------

--------------------------------------------------------------------------------------------------------------------------

--------------------------------------------------------------------------------------------------------------------------

--------------------------------------------------------------------------------------------------------------------------

--------------------------------------------------------------------------------------------------------------------------

--------------------------------------------------------------------------------------------------------------------------

--------------------------------------------------------------------------------------------------------------------------

--------------------------------------------------------------------------------------------------------------------------

--------------------------------------------------------------------------------------------------------------------------

--------------------------------------------------------------------------------------------------------------------------

--------------------------------------------------------------------------------------------------------------------------

--------------------------------------------------------------------------------------------------------------------------

--------------------------------------------------------------------------------------------------------------------------

--------------------------------------------------------------------------------------------------------------------------

--------------------------------------------------------------------------------------------------------------------------

==========================================================================================================================
</TABLE>

                                      B-15

<PAGE>   119



                                    EXHIBIT C

                    INSTRUCTION FROM PURCHASE CONTRACT AGENT
                               TO COLLATERAL AGENT

[Collateral Agent Address]


                  Re:      Equity Units of NRG Energy, Inc. (the "Company")

                  We hereby notify you in accordance with Section [4.1] [4.2] of
the Pledge Agreement, dated as of _________, 2001, (the "Pledge Agreement")
among the Company, yourselves, as Collateral Agent, Custodial Agent and
Securities Intermediary and ourselves, as Purchase Contract Agent and as
attorney-in-fact for the holders of [Corporate Units] [Treasury Units] from time
to time, that the holder of the Securities listed below (the "Holder") has
elected to substitute [$_____ aggregate principal amount of Treasury Securities]
[$_______ aggregate principal amount of Debentures or the appropriate Applicable
Ownership Interest of the Treasury Portfolio, as the case may be,] in exchange
for an equal Value of [Pledged Debentures or the appropriate Applicable
Ownership Interest of the Treasury Portfolio, as the case may be,] [Pledged
Treasury Securities] held by you in accordance with the Pledge Agreement and
has delivered to us a notice stating that the Holder has Transferred [Treasury
Securities] [Debentures or the appropriate Applicable Ownership Interest of the
Treasury Portfolio, as the case may be,] to you, as Collateral Agent. We hereby
instruct you, upon receipt of such [Pledged Treasury Securities] [Pledged
Debentures or the appropriate Applicable Ownership Interest of the Treasury
Portfolio, as the case may be,], and upon the payment by such Holder of any
applicable fees, to release the [Debentures or the appropriate Applicable Owner
ship Interest of the Treasury Portfolio, as the case may be,] [Treasury
Securities] related to such [Corporate Units] [Treasury Units] to us in
accordance with the Holder's instructions. Capitalized terms used herein but not
defined shall have the meaning set forth in the Pledge Agreement.


Date:_____________                  _________________________________
                                            By:______________________
                                            Name:
                                            Title:
                                    Signature Guarantee:_____________




<PAGE>   120

Please print name and address of Registered Holder electing to substitute
[Treasury Securities] [Debentures or the appropriate Applicable Ownership
Interest of the Treasury Portfolio, as the case may be,] for the [Pledged
Debentures or the appropriate Applicable Ownership Interest of the Treasury
Portfolio, as the case may be,] [Pledged Treasury Securities]:


---------------------------                 ---------------------------------
           Name                             Social Security or other Taxpayer
                                            Identification Number, if any

---------------------------
         Address
---------------------------

---------------------------


                                       C-2

<PAGE>   121



                                    EXHIBIT D

                     INSTRUCTION TO PURCHASE CONTRACT AGENT


[Purchase Contract Agent Address]



                  Re:      Equity Units of NRG Energy, Inc. (the "Company")

                  The undersigned Holder hereby notifies you that it has
delivered to                    , as Collateral Agent, [$_______ aggregate
principal amount of Treasury Securities] [$        aggregate principal amount of
Debentures or the appropriate Applicable Ownership Interest of the Treasury
Portfolio, as the case may be,] in exchange for an equal Value of [Pledged
Debentures or the appropriate Applicable Ownership Interest of the Treasury
Portfolio, as the case may be,] [Pledged Treasury Securities] held by the
Collateral Agent, in accordance with Section [4.1], [4.2] of the Pledge
Agreement, dated February __, 2001 (the "Pledge Agreement"), between you, the
Company and the Collateral Agent. The undersigned Holder has paid the Collateral
Agent all applicable fees relating to such exchange. The undersigned Holder
hereby instructs you to instruct the Collateral Agent to release to you on
behalf of the undersigned Holder the [Pledged Debentures or the appropriate
Applicable Ownership Interest of the Treasury Portfolio] [Pledged Treasury
Securities] related to such [Corporate Units] [Treasury Units]. Capitalized
terms used herein but not defined shall have the meaning set forth in the Pledge
Agreement.


Dated:_____________                         __________________________________
                                            Signature

                                            Signature Guarantee:______________


Please print name and address of Registered Holder:

___________________________                 _________________________________
           Name                             Social Security or other Taxpayer
                                            Identification Number, if any

__________________________
         Address
__________________________

__________________________


<PAGE>   122



                                    EXHIBIT E

                        NOTICE TO SETTLE BY SEPARATE CASH

[Purchase Contract Agent Address]


                  Re:      Equity Units of NRG Energy, Inc. (the "Company")

                  The undersigned Holder hereby irrevocably notifies you in
accordance with Section 5.4 of the Purchase Contract Agreement dated as of
__________, 2001 among the Company and yourselves, as Purchase Contract Agent
and as Attorney-in-Fact for the Holders of the Purchase Contracts, that such
Holder has elected to pay to the Collateral Agent, on or prior to 11:00 a.m. New
York City time, on the Business Day immediately preceding the Purchase Contract
Settlement Date, (in lawful money of the United States by [certified or cashiers
check or] wire transfer, in each case in immediately available funds),
$_________ as the Purchase Price for the shares of Common Stock issuable to such
Holder by the Company under the related Purchase Contract on the Purchase
Contract Settlement Date. The undersigned Holder hereby instructs you to notify
promptly the Collateral Agent of the undersigned Holders election to make such
cash settlement with respect to the Purchase Contracts related to such Holder's
[Corporate Units] [Treasury Units].

Dated:_____________                         __________________________________
                                            Signature

                                            Signature Guarantee:______________

Signatures must be guaranteed by an "eligible guarantor institution" meeting the
requirements of the Registrar, which requirements include membership or
participation in the Security Transfer Agent Medallion Program ("STAMP") or such
other "signature guarantee program" as may be determined by the Registrar in
addition to, or in substitution for, STAMP, all in accordance with the
Securities Exchange Act of 1934, as amended.

Please print name and address of Registered Holder:


___________________________                 _________________________________
           Name                             Social Security or other Taxpayer
                                            Identification Number, if any

__________________________
         Address
__________________________

__________________________