Document:

<PAGE>

                                                                     EXHIBIT 4.3

================================================================================

                         SECOND SUPPLEMENTAL INDENTURE

                         dated as of           , 2001

                                      to

                                   INDENTURE

                         dated as of November 1, 2000

                       AMEREN ENERGY GENERATING COMPANY

                                      to

                       THE BANK OF NEW YORK, as Trustee

================================================================================

                                 $425,000,000

              $225,000,000  7.75% Senior Notes, Series C Due 2005
              $200,000,000  8.35% Senior Notes, Series D Due 2010
<PAGE>

     SECOND SUPPLEMENTAL INDENTURE (the "Second Supplemental Indenture"), dated
as of          , 2001, to the Indenture, dated as of November 1, 2000 (the
"Original Indenture"), from AMEREN ENERGY GENERATING COMPANY, an Illinois
corporation (together with its successors and assigns, the "Issuer"), its
principal office and mailing address being at One Ameren Plaza, 1901 Chouteau
Avenue, P.O. Box 66149, St. Louis, Missouri 63166-6149, to THE BANK OF NEW YORK,
as trustee (the "Trustee"), its office and mailing address being at 101 Barclay
Street, New York, New York 10286.

                             W I T N E S S E T H:

     WHEREAS, the Issuer and the Trustee have heretofore executed and
delivered the Original Indenture to provide for the issuance from time to time
of the Issuer's Securities (as defined in the Original Indenture) to be issued
in one or more series;

     WHEREAS, Sections 2.1 and 7.1 of the Original Indenture provide, among
other things, that the Issuer and the Trustee may enter into indentures
supplemental to the Original Indenture for, among other things, the purpose of
establishing the designation, form, terms and provisions of Securities of any
series as permitted by Sections 2.1 and 7.1 of the Original Indenture;

     WHEREAS, the Issuer has heretofore issued two (2) series of Securities
designated (i) 7.75% Senior Notes, Series A due 2005 (the "Series A Notes") and
(ii) 8.35% Senior Notes, Series B due 2010 (the "Series B Notes" and, together
with the Series A Notes, the "Old Notes");

     WHEREAS, the Old Notes were sold to a group consisting of Lehman Brothers
Inc., Chase Securities Inc., Banc of America Securities LLC, Banc One Capital
Markets, Inc. and BNY Capital Markets, Inc. (collectively, the "Initial
Purchasers");

     WHEREAS, sales and transfers of the Old Notes are restricted to qualified
institutional investors pursuant to Rule 144A under the Securities Act of 1933,
as amended (the "Securities Act") and qualified buyers outside the United States
pursuant to Regulation S under the Securities Act;

     WHEREAS, the Issuer and the Initial Purchasers entered into a Registration
Rights Agreement, dated as of November 1, 2000 (the "Registration Rights
Agreement"), pursuant to which the Issuer agreed, for the benefit of the Holders
of the Old Notes, to file a registration statement relating to an exchange offer
allowing the Holders of the Old Notes to exchange their transfer restricted Old
Notes for a new series of notes that are identical in all material respects to
the Old Notes except that the new series of notes will not contain the transfer
restrictions or registration rights (and certain related liquidated damages
provisions) applicable to the Old Notes and the new series of notes would be
registered under the Securities Act;

     WHEREAS, the Issuer (i) desires the issuance of two (2) series of
Securities to be designated as hereinafter provided and (ii) has requested the
Trustee to enter into this Second Supplemental Indenture for the purpose of
establishing the designation, form, terms and provisions of the Securities of
such series;
<PAGE>

     WHEREAS, the Original Indenture restricts the Issuer from incurring any
Indebtedness other than Permitted Indebtedness (each as defined in the Original
Indenture), which expressly includes the two (2) series of Securities
established hereby;

     WHEREAS, all action on the part of the Issuer necessary to authorize the
issuance of said Securities under the Original Indenture and this Second
Supplemental Indenture (the Original Indenture, as supplemented by this Second
Supplemental Indenture, being hereinafter called the "Indenture") has been duly
taken; and

     WHEREAS, all acts and things necessary to make said Securities, when
executed by the Issuer and authenticated and delivered by the Trustee as
provided in the Original Indenture, the legal, valid and binding obligations of
the Issuer, and to constitute these presents a valid and binding supplemental
indenture according to its terms, have been done and performed, and the
execution of this Second Supplemental Indenture and the creation and issuance
under the Indenture of said Securities have in all respects been duly
authorized, and the Issuer, in the exercise of the legal right and power vested
in it, executes this Second Supplemental Indenture and proposes to create,
execute, issue and deliver said Securities;

     NOW, THEREFORE, in order to establish the designation, form, terms and
provisions of, and to authorize the authentication and delivery of, said
Securities, and in consideration of the acceptance of said Securities by the
Holders thereof and of other good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged, the parties hereto agree as
follows:

                                   ARTICLE I

                                  DEFINITIONS
                                  -----------

     Capitalized terms not otherwise defined herein shall have the meanings set
forth in the Original Indenture.

                                   ARTICLE II

                            THE TERMS OF THE NOTES
                            ----------------------

     Section 2.1 Terms of 7.75% Senior Notes, Series C due 2005 and 8.35% Senior
                 ---------------------------------------------------------------
Notes, Series D due 2010. (a) There is hereby created one (1) series of
------------------------
Securities designated: 7.75% Senior Notes, Series C due 2005 (the "Series C
Notes"). The Series C Notes shall be limited to $225,000,000 aggregate principal
amount outstanding less the amount of any Series A Notes which remain
outstanding and un-exchanged following completion of the Issuer's exchange offer
for the Series A Notes as contemplated by its prospectus dated            , 2001
(the "Prospectus"). Upon delivery of a written order to the Trustee in
accordance with the provisions of Section 2.1 of the Original Indenture, the
Trustee shall authenticate and deliver the Series C Notes. Such written order
shall specify the amount of the Series C Notes to be authenticated and the date
on which such Series C Notes are to be authenticated, which will be the date the
Series C Notes are issued in exchange for the Series A Notes.

                                       2
<PAGE>

            (b)   There is hereby created one (1) series of Securities
designated: 8.35% Senior Notes, Series D due 2010 (the "Series D Notes" and,
together with the Series C Notes, the "Exchange Notes"). The Series D Notes
shall be limited to $200,000,000 aggregate principal amount outstanding less the
amount of any Series B Notes which remain outstanding and un-exchanged following
completion of the Issuer's exchange offer for the Series B Notes as contemplated
by the Prospectus. Upon delivery of a written order to the Trustee in accordance
with the provisions of Section 2.1 of the Original Indenture, the Trustee shall
authenticate and deliver the Series D Notes. Such written order shall specify
the amount of the Series D Notes to be authenticated and the date on which such
Series D Notes are to be authenticated, which will be the date the Series D
Notes are issued in exchange for the Series B Notes.

            (c)   The Exchange Notes of each series shall be substantially in
the form of Exhibit A hereto.

     Section 2.2  Terms of Exchange Notes Issued Hereunder in Global Form.
                  -------------------------------------------------------

            (a)   So long as The Depository Trust Company ("DTC") or its nominee
is the registered owner or Holder of a Global Security, DTC or its nominee, as
the case may be, will be considered the sole owner or Holder of the Exchange
Notes represented by such Global Security for all purposes under the Original
Indenture and under the Exchange Notes. No beneficial owner of an interest in a
Global Security will be able to transfer that interest except in accordance with
DTC's applicable procedures unless the Issuer shall issue certificates for the
Exchange Notes in definitive registered form.

            (b)   All payments of the principal of, and interest and additional
amounts and premium, if any, on, a Global Security will be made to DTC or its
nominees, as the registered owners thereof.

            (c)   Transfers between participants in DTC will be effected in the
ordinary way in accordance with DTC rules and will be settled in same-day funds.

            (d)   Certificated definitive Exchange Notes of a series may be in
denominations of less than $100,000 to the extent any redemption has reduced
such Holder's aggregate holding of such Exchange Notes of the same series to
less than $100,000.

            (e)   If any redemption affecting the Exchange Notes of a series
would result in the amount to be paid to a Holder of such affected Exchange Note
in respect of such redemption not to equal $1,000 or an integral multiple
thereof, the Issuer shall instruct the Trustee to round the amount to be paid to
such Holder to the nearest $1,000 so that the amount to be paid to such Holder
equals $1,000 or an integral multiple thereof.

            (f)   Except in the limited circumstances described under Section
2.2(g) below, beneficial interest in a Global Security will only be recorded by
book-entry and owners of beneficial interest in a Global Security will not be
entitled to receive physical delivery of certificates representing Securities.

            (g)   If (i) the Issuer notifies the Trustees in writing that DTC or
any successor depository is unwilling or unable to continue as a depository for
a Global Security or ceases to be

                                       3
<PAGE>

a "clearing agency" registered under the Exchange Act and a successor depository
is not appointed by the Issuer within 90 days of such notice, (ii) the Issuer,
at its option, notifies the Trustee in writing that it elects to cause the
issuance of the Securities issued hereunder to be in certificated form or (iii)
during an Event of Default, a holder of a beneficial interest in a Global
Security requests the issuance of certificated Securities representing such
holder's interest then, the Issuer shall issue certificates for the Securities
in definitive registered form substantially in the form attached hereto in
exchange for the Global Security outstanding.

            (h)   The holder of a certificated definitive registered Security
may transfer such Security in whole or in part by surrendering it at the
Corporate Trust Office of the Trustee in accordance with the terms of the
Indenture and such Security.

     Section 2.3  Interest, Principal, Maturity Date and Regular Record Date.
                  ----------------------------------------------------------
Each Exchange Note shall bear interest on the unpaid principal amount thereof
from time to time outstanding from the last interest payment date through which
interest shall have been paid on the Old Note for which it is exchanged, as the
case may be, until such amount is paid in full at the rate of interest set forth
in the form of such Exchange Note attached hereto. The principal amount of each
Exchange Note shall be due and payable at maturity as set forth in the form of
Exchange Note attached hereto.

     Payment of principal of, premium, if any, and interest on the Exchange
Notes of each series shall be made, as provided in Sections 2.4, 2.10, 3.2 and
3.4 of the Original Indenture except that the final payment of principal of any
series of the Exchange Notes shall be made on the due date therefor to the
account of the Holder as such account shall appear in the Security Register,
which amount shall be payable upon presentation and surrender of such Exchange
Note at the office of the Issuer.

     Each Exchange Note of a series shall mature on the date and in the amounts
set forth thereon.

     The record date applicable to the Exchange Notes of each series issued
hereunder shall be as set forth in the form of Exchange Note of such series
attached hereto.

     All payments of principal and interest with respect to certificated
Exchange Notes will be made by bank check mailed on the Interest Payment Date to
the address of such Holder on the Security Register or, for Holders of at least
U.S. $1,000,000 in aggregate principal amount of Exchange Notes of a series, by
wire transfer on the Interest Payment Date to a dollar account maintained by the
payee with a bank in The City of New York; provided, that a written request from
such Holder to such effect designating such account is received by the Trustee
and the Issuer or the paying agent no later than the record date immediately
preceding such Interest Payment Date.  Unless such designation is revoked, any
such designation made by such person with respect to such certificated Exchange
Notes will remain in effect with respect to any future payments with respect to
such certificated Exchange Note payable to such person.

     Section 2.4  Redemption.
                  ----------

            (a)   Optional Redemption. The Exchange Notes of either series
                  -------------------
issued hereunder are subject to optional redemption, in whole or in part, at any
time at the option of the

                                       4
<PAGE>

Issuer at a redemption price equal to the outstanding principal amount of the
Exchange Notes of such series being so redeemed plus accrued and unpaid interest
thereon to the date fixed for redemption together with the Applicable Premium
applicable thereto.

            (b)   Applicable Premium. As used herein, "Applicable Premium" means
                  ------------------
an amount calculated as of the date (the "Determination Date") fixed for the
redemption of the Exchange Notes of such series as follows:

            (i)   the average life of the remaining scheduled payments of
            principal in respect of Outstanding Exchange Notes of such series
            (the "Remaining Average Life") shall be calculated as of the
            Determination Date;

            (ii) the yield to maturity calculated as of a date not more than
            five days prior to the Determination Date for the United States
            Treasury security having an average life equal to the Remaining
            Average Life of such series and trading in the secondary market at
            the price closest to the principal amount thereof (the "Primary
            Issue"); provided, however, that if no United States Treasury
            security has an average life equal to the Remaining Average Life of
            such series, the yields (the "Other Yields") for the two maturities
            of United States treasury securities having average lives most
            closely corresponding to such Remaining Average Life and trading in
            the secondary market at the price closest to the principal amount
            thereof shall be calculated, and the yield to maturity for the
            Primary Issue shall be the yield interpolated or extrapolated from
            such Other Yields on a straight line basis, rounding in each of such
            relevant periods to the nearest month;

            (iii) the discounted present value of the then remaining scheduled
            payments of principal and interest (but excluding that portion of
            any scheduled payment of interest that is actually due and paid on
            the Determination Date) in respect of the Outstanding Exchange Notes
            of such series shall be calculated as of the Determination Date
            using a discount factor equal to the sum of (x) the yield to
            maturity for the Primary Issue, plus (y) 25 basis points; and
                                            ----

            (iv)  the amount of Applicable Premium in respect of the Exchange
            Notes of such series to be redeemed shall be an amount equal to (x)
            the discounted present value of such Exchange Notes to be redeemed
            determined in accordance with clause (iii) above, minus (y) the
                                                              -----
            unpaid principal amount of such Exchange Notes; provided, however,
            that the Applicable Premium shall not be less than zero; and

            (v)   such calculation shall be made by an Investment Banker.

     Section 2.5  Registered Notes Issued Upon Exchange. The Exchange Notes
                  -------------------------------------
shall be registered under the Securities Act and the transfer restrictions set
forth in Section 2.6 of the Original Indenture shall not apply to the transfer
of the Exchange Notes and the Legend referred to in Section 2.6 of the Original
Indenture shall not be required to be placed on each certificate representing
the Exchange Notes. Pursuant to the Issuer's written order to the Trustee in
accordance with the provisions of Section 2.1 of the Original Indenture, the
Issuer shall execute and the Trustee shall authenticate and deliver (a) Series C
Notes in denominations of $100,000

                                       5
<PAGE>

original principal amount in exchange for each $100,000 principal amount of
outstanding Series A Notes, and in integral multiples of $1,000 original
principal amount in exchange for each $1,000 in excess thereof, and (b) Series D
Notes in denominations of $100,000 original principal amount in exchange for
each $100,000 principal amount of outstanding Series B Notes, and in integral
multiples of $1,000 original principal amount in exchange for each $1,000 in
excess thereof, in each case if properly tendered by the Holder thereof together
with a completed letter of transmittal in the form attached hereto as Exhibit B
which is incorporated herein by this reference. Upon the surrender of any Old
Notes as contemplated herein, such Old Notes shall be cancelled by the Trustee
and no further amounts shall be due and payable on such Old Notes (except that
any accrued but unpaid liquidated damages due pursuant to the Registration
Rights Agreement shall remain due and payable) and (i) any interest accrued and
unpaid on the Series A Notes through the date of such exchange, which shall be
the date of authentication of the Series C Notes, shall from and after such
exchange be represented by the Series C Notes and shall be payable as provided
in the Series C Notes and (ii) any interest accrued and unpaid on the Series B
Notes through the date of such exchange, which shall be the date of
authentication of the Series D Notes, shall from and after such exchange be
represented by the Series D Notes and shall be payable as provided in the Series
D Notes. Interest shall accrue on the Series C Notes as described in Section 2.3
hereof; provided that the amount payable on the Series C Notes pursuant to
Section 2.3 will be offset by the amount of interest accrued on the Series A
Notes prior to the date of exchange which is thereafter deemed payable on the
Series C Notes under this Section 2.5. Interest shall accrue on the Series D
Notes as described in Section 2.3 hereof; provided that the amount payable on
the Series D Notes pursuant to Section 2.3 will be offset by the amount of
interest accrued on the Series B Notes prior to the date of exchange which is
thereafter deemed payable on the Series D Notes under this Section 2.5.

     Section 2.6  Treatment of Series.  For all purposes of the Indenture the
                  -------------------
Series A Notes and the Series C Notes shall be treated as the same series and
the Holders of the Series A Notes and the Series C Notes shall vote and consent
together on all matters as one class and none of the Holders of the Series A
Notes or the Series C Notes shall have the right to vote or consent as a
separate class on any matter.  For all purposes of the Indenture the Series B
Notes and the Series D Notes shall be treated as the same series and the Holders
of the Series B Notes and the Series D Notes shall vote and consent together on
all matters as one class and none of the Holders of the Series B Notes or the
Series D Notes shall have the right to vote or consent as a separate class on
any matter.

                                  ARTICLE III

                                 MISCELLANEOUS
                                 -------------

     Section 3.1  Execution of Supplemental Indenture.  This Second Supplemental
                  -----------------------------------
Indenture is executed and shall be construed as an indenture supplemental to the
Original Indenture and, as provided in the Original Indenture, this Second
Supplemental Indenture forms a part thereof.

     Section 3.2  Concerning the Trustee.  The Trustee shall not be responsible
                  ----------------------
in any manner for or with respect to the validity or sufficiency of this Second
Supplemental Indenture,

                                       6
<PAGE>

or the due execution hereof by the Issuer, or for or with respect to the
recitals and statements contained herein, all of which recitals and statements
are made solely by the Issuer.

     Section 3.3  Counterparts.  This Second Supplemental Indenture may be
                  ------------
executed in any number of counterparts, each of which when so executed shall be
deemed to be an original; but all such counterparts shall together constitute
but one and the same instrument.

     Section 3.4  GOVERNING LAW.  THIS SECOND SUPPLEMENTAL INDENTURE AND EACH
                  -------------
EXCHANGE NOTE ISSUED HEREUNDER SHALL, PURSUANT TO SECTION 5-1401 OF THE NEW YORK
GENERAL OBLIGATIONS LAW, BE GOVERNED BY THE LAW OF THE STATE OF NEW YORK,
WITHOUT REFERENCE TO THE CHOICE OF LAW PROVISIONS THEREOF (OTHER THAN SUCH
SECTION 5-1401).

                                       7
<PAGE>

     IN WITNESS WHEREOF, the parties hereto have caused this Second Supplemental
Indenture to be duly executed as of            , 2001.

                                               AMEREN ENERGY GENERATING
                                               COMPANY, as Issuer

                                               By: _____________________________
                                                   Name:
                                                   Title:

                                               THE BANK OF NEW YORK, as Trustee

                                               By: _____________________________
                                                   Name:
                                                   Title:
<PAGE>

                                                                       EXHIBIT A
                               FORM OF SECURITY

     UNLESS THIS CERTIFICATE IS PRESENTED BY AN AUTHORIZED REPRESENTATIVE OF THE
DEPOSITORY TRUST COMPANY TO THE ISSUER OR ITS AGENT FOR REGISTRATION OF
TRANSFER, EXCHANGE OR PAYMENT, AND ANY CERTIFICATE ISSUED IN EXCHANGE FOR THIS
CERTIFICATE OR ANY PORTION HEREOF IS REGISTERED IN THE NAME OF CEDE & CO. OR TO
SUCH OTHER ENTITY AS IS REQUESTED BY AN AUTHORIZED REPRESENTATIVE OF THE
DEPOSITORY TRUST COMPANY OR SUCH OTHER NAME AS IS 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 OR TO ANY PERSON OTHER THAN THE DEPOSITORY TRUST COMPANY OR A NOMINEE THEREOF
IS WRONGFUL INASMUCH AS THE REGISTERED OWNER HEREOF, CEDE & CO., HAS AN INTEREST
HEREIN.

     TRANSFERS OF THIS GLOBAL SECURITY SHALL BE LIMITED TO TRANSFERS IN WHOLE,
BUT NOT IN PART, TO NOMINEES OF THE DEPOSITORY TRUST COMPANY OR TO A SUCCESSOR
THEREOF OR SUCH SUCCESSOR'S NOMINEE AND TRANSFERS OF PORTIONS OF THIS GLOBAL
SECURITY SHALL BE LIMITED TO TRANSFERS MADE IN ACCORDANCE WITH THE RESTRICTIONS
SET FORTH IN SECTION 2.6 OF THE INDENTURE REFERRED TO ON THE REVERSE HEREOF.]

                        [FORM OF FACE OF EXCHANGE NOTE]

                          CUSIP [     ][     ][     ]

                                 [Common Code]
                                 [ISIN][    ]

No.

                                       $
                       AMEREN ENERGY GENERATING COMPANY
                 /*/ % Senior Notes, Series /**/ Due 20 /***/

     Ameren Energy Generating Company (the "Issuer"), for value received hereby
                                            ------
promises to pay to                     or registered assigns the principal sum
of                    Dollars at the Issuer's office or agency for said purpose
as provided in the Indenture referred to herein, on November 1,/***/      in
such coin or currency of the United States of America as at the time of payment
shall be legal tender for the payment of public and private debts, and to pay
interest, semi-annually in
______________________

/*/    Insert 7.75% or 8.35% as applicable.
/**/   Insert C or D as applicable.
/***/  Insert 2005 or 2010 as applicable.
<PAGE>

arrears on May 1 and November 1 of each year, commencing November 1, 2001, on
said principal sum in like coin or currency at the rate per annum set forth
above at said offices or agencies from the date of original issuance or the most
recent interest payment date to which interest on the Senior Notes of this
series has been paid or duly provided for. Notwithstanding the foregoing, if the
date hereof is after April 15 or October 15, as the case may be, and before the
following May 1 or November 1, this Senior Note shall bear interest from such
May 1 or November 1; provided, that if the Issuer shall default in the payment
of interest due on such May 1 or November 1, then this Senior Note shall bear
interest from the next preceding May 1 or November 1 to which interest on the
Senior Notes of this series has been paid or duly provided for. The interest so
payable on any May 1 or November 1 will, except as otherwise provided in the
Indenture referred to on the reverse hereof, be paid to the Person in whose name
this Senior Note is registered at the close of business on the 15th day of April
or the 15th day of October preceding such May 1 or November 1, whether or not
such day is a Business Day; provided, that principal, premium, if any, and
interest shall be paid by mailing on the interest payment date a check for such
to or upon the written order of the registered Holders of Senior Notes of this
series entitled thereto at their last address as it appears on the Senior Notes
Register or, upon written application to the Trustee by a Holder of $1,000,000
or more in aggregate principal amount of Senior Notes of this series, by wire
transfer on the interest payment date of immediately available funds to an
account maintained by such Holder with a bank or other financial institution.
Interest on this Senior Note shall be computed on the basis of a 360-day year
comprised of twelve 30-day months. Additional Interest shall accrue on this
Senior Note under the circumstances provided for in the Registration Rights
Agreement.

     Interest on overdue principal and (to the extent permitted by applicable
law) on overdue installments of interest (including without limitation during
the 5-day period referred to in Section 4.1(b) of the Indenture) shall accrue at
the rate per annum set forth above.

     The Senior Notes of this series are payable on a parity basis with the
Issuer's /*/ % Senior Notes, Series /*****/ Due 20 /***/ (the "Old Notes")
issued under the Indenture and the First Supplemental Indenture, dated as of
November 1, 2000 in the aggregate principal amount of $        /****/. The
Senior Notes of this series are being issued in exchange for a like principal
amount of Old Notes and the combined aggregate principal amount of the Senior
Notes of this series and the Old Notes outstanding at any one time is limited to
$        /****/. Pursuant to the Indenture, the Old Notes and the Senior Notes
of this series shall be treated as the same series and the holders of the Old
Notes and the Senior Notes of this series shall vote and consent together on all
matters as one class and none of the holders of the Old Notes or the Senior
Notes of this series shall have the right to vote or consent as a separate class
on any matter.

     Reference is made to the further provisions set forth on the reverse
hereof.  Such further provisions shall for all purposes have the same effect as
though fully set forth at this place.

_______________________

/*/    Insert 7.75% or 8.35% as applicable.
/***/  Insert 2005 or 2010 as applicable.
/****/ Insert $225,000,000 or $200,000,000 as applicable.
/*****/Insert A or B as applicable.
<PAGE>

     This Senior Note shall not be entitled to any benefit under the Indenture,
or be valid or obligatory, until the certificate of authentication hereon shall
have been duly signed by the Trustee acting under the Indenture.

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

                                                THE BANK OF NEW YORK, as Trustee

                                                By:_____________________________
                                                   Name:
                                                   Title:
(SEAL)
Attested:

By:______________________________
Name:
Title:

_______________
<PAGE>

                      [FORM OF REVERSE OF EXCHANGE NOTE]

                       AMEREN ENERGY GENERATING COMPANY

                  /*/ % Senior Notes, Series /**/ Due 20  /***/

     This Senior Note is one of a duly authorized issue of debt securities of
the Issuer, limited to the aggregate principal amount of $             /****/
(except as otherwise provided in the Indenture mentioned below), issued or to be
issued pursuant to an Indenture dated as of November 1, 2000 as supplemented by
the Second Supplemental Indenture dated as of                , 2001 (as so
supplemented, the "Indenture"), duly executed and delivered by the Issuer to the
                   ---------
Trustee.  Reference is hereby made to the Indenture and all indentures
supplemental thereto for a description of the rights, limitations of rights,
obligations, duties and immunities thereunder of the Trustee, the Issuer and the
Holders (the words "Holders" or "Holder" meaning the registered holders or
                    -------      ------
registered holder) of the Senior Notes.  Capitalized terms used herein, but not
otherwise defined herein, shall have the meanings assigned to them in the
Indenture.

     In case an Event of Default shall have occurred and be continuing, the
principal of all the Securities may be declared due and payable, in the manner
and with the effect, and subject to the conditions, provided in the Indenture.
The Indenture provides that in certain events such declaration and its
consequences may be waived by the Holders of a majority in aggregate principal
amount of the Securities then Outstanding and that, prior to any such
declaration, such Holders may waive any past default under the Indenture and its
consequences except a default in the payment of principal of or premium, if any,
or interest on any of the Securities and as otherwise provided in the Indenture.
Any such consent or waiver by the Holder of this Senior Note (unless revoked as
provided in the Indenture) shall be conclusive and binding upon such Holder and
upon all future Holders and owners of this Senior Note and any Security which
may be issued in exchange or substitution hereof, whether or not any notation
thereof is made upon this Senior Note or such other Security.

     The Indenture permits the Issuer and the Trustee, with the consent of the
Holders of not less than a majority in aggregate principal amount of the
Securities of all series at the time Outstanding considered as one class,
evidenced as in the Indenture provided, to modify the Indenture or any
supplemental indentures or the rights of the Holders of the Senior Notes;
provided that no such modification shall (a) change the Stated Maturity of the
--------
principal of, or any installment of principal of or interest on, any Security,
or reduce the principal amount thereof, or reduce the rate or extend the time of
payment of interest thereon, or reduce any amount payable on redemption thereof
or impair or affect the right of any Holder of the Security to institute suit
for the payment thereof without the consent of the Holder of each Security so
affected; or (b)(i) reduce the aforesaid percentage of Securities, the consent
of the Holders of

_________________

/*/    Insert 7.75% or 8.35% as applicable.
/**/   Insert C or D as applicable.
/***/  Insert 2005 or 2010 as applicable.
/****/ Insert $225,000,000 or $200,000,000 as applicable.
<PAGE>

which is required for any such modification or the percentage of Securities, the
consent of Holders of which is required for any waiver provided for in the
Indenture; (ii) change any obligation of the Issuer to maintain an office or
agency for payment of and transfer and exchange of the Securities; or (iii) make
certain changes to provisions relating to waiver or to the provision for
supplementing the Indenture; in each case without the consent of the Holders of
all Securities then Outstanding.

     No reference herein to the Indenture and no provision of this Senior Note
or of the Indenture shall alter or impair the obligation of the Issuer, which is
absolute and unconditional, to pay the principal of and premium, if any, and
interest on this Senior Note at the place, times, and rate, and in the currency,
herein prescribed.

     The Senior Notes are issuable only as registered Senior Notes without
coupons in denominations of $100,000 and any integral multiple of $1,000 in
excess thereof.

     At the office or agency of the Issuer referred to on the face hereof and in
the manner and subject to the limitations provided in the Indenture, Senior
Notes may be presented for exchange for a like aggregate principal amount of
Senior Notes of other authorized denominations.

     Upon due presentment for registration of transfer of this Senior Note at
the above-mentioned office or agency of the Issuer, a new Senior Note or Senior
Notes of authorized denominations, for a like aggregate principal amount, will
be issued to the transferee as provided in the Indenture.  No service charge
shall be made for any such transfer, but the Issuer may require payment of a sum
sufficient to cover any tax or other governmental charge that may be imposed in
relation thereto.

     The Senior Notes may be redeemed in whole or in part (if in part, by lot or
by such other method as the Trustee shall deem fair or appropriate) prior to
Stated Maturity at the option of the Issuer, upon mailing a notice of such
redemption not less than 30 nor more than 60 days prior to the date fixed for
redemption to the Holders of Senior Notes, all as provided in the Indenture, at
a redemption price equal to the principal amount thereof plus accrued and unpaid
interest thereon, if any, to the date of redemption, plus the Applicable
Premium.

     Subject to payment by the Issuer of a sum sufficient to pay the amount due
on redemption, interest on this Senior Note shall cease to accrue upon the date
duly fixed for redemption of this Senior Note.

     The Issuer, the Trustee, and any authorized agent of the Issuer or the
Trustee, may deem and treat the registered Holder hereof as the absolute owner
of this Senior Note (whether or not this Senior Note shall be overdue and
notwithstanding any notation of ownership or other writing hereon made by anyone
other than the Issuer or the Trustee or any authorized agent of the Issuer or
the Trustee), for the purpose of receiving payment of, or on account of, the
principal hereof and premium, if any, and, subject to the provisions on the face
hereof, interest hereon and for all other purposes, and neither the Issuer nor
the Trustee nor any authorized agent of the Issuer or the Trustee shall be
affected by any notice to the contrary.

     No recourse shall be had for the payment of the principal of, or premium,
if any, or the interest on this Senior Note, for any claim based hereon, or
otherwise in respect hereof, or based
<PAGE>

on or in respect of the Indenture or any indenture supplemental thereto, against
any incorporator, shareholder, officer or director, as such, past, present or
future, of the Issuer or of any successor corporation, either directly or
through the Issuer or any successor corporation, whether by virtue of any
constitution, statute or rule of law or by the enforcement of any assessment or
penalty or otherwise, all such liability being, by the acceptance hereof and as
part of the consideration for the issue hereof, expressly waived and released.
<PAGE>

               [FORM OF TRUSTEE'S CERTIFICATE OF AUTHENTICATION]

Dated:

     This is one of the Senior Notes referred to in the within-mentioned
Indenture.

                                              THE BANK OF NEW YORK, as Trustee

                                              By:_______________________________
                                                      Authorized Signatory
<PAGE>

                             [FORM OF ASSIGNMENT]

I or we assign and transfer this Security to:

             (Insert assignee's social security or tax I.D. number)

_________________________________________________________
_________________________________________________________
_________________________________________________________
_________________________________________________________
(Print or type name, address and zip code of assignee)

and irrevocably appoint:

_______________________________________________
_______________________________________________

Agent to transfer this Security on the books of the Issuer.  The Agent may
substitute another to act for him.

Date: ___________________         Your Signature: ___________________

                                         ____________________________
                                         (Sign exactly as your name
                                         appears on the other side of
                                         this Security)

               *Signature Guarantee:________________________

               *Signatures must be guaranteed by an "eligible guarantor
          institution" meeting the requirements of the Registrar, which
          requirements include membership or participation in 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.
<PAGE>

                                                                       EXHIBIT B

                             LETTER OF TRANSMITTAL

                                [To be attached]<PAGE>

                                                                     EXHIBIT 4.6

                       AMEREN ENERGY GENERATING COMPANY
                         REGISTRATION RIGHTS AGREEMENT

                                                                November 1, 2000

Lehman Brothers Inc.
Chase Securities Inc.
Banc of America Securities LLC
Banc One Capital Markets, Inc.
BNY Capital Markets, Inc.
c/o Lehman Brothers Inc.
3 World Financial Center
New York, NY 10285

Ladies and Gentlemen:

     Ameren Energy Generating Company, an Illinois corporation (the "Company"),
proposes to issue and sell severally and not jointly to Lehman Brothers Inc.,
Chase Securities Inc., Banc of America Securities LLC, Banc One Capital Markets,
Inc. and BNY Capital Markets, Inc. (collectively, the "Initial Purchasers"), on
the terms set forth in a note purchase agreement dated October 25, 2000 (the
"Purchase Agreement"), $225,000,000 aggregate principal amount of 7.75% Senior
Notes, Series A due 2005 (the "Series A Notes") and $200,000,000 aggregate
principal amount of 8.35% Senior Notes, Series B due 2010 (the "Series B Notes"
and collectively with the Series A Notes, the "Notes").  The Notes will be
issued pursuant to an Indenture, dated as of November 1, 2000 and a First
Supplemental Indenture, dated as of November 1, 2000 (collectively, the
"Indenture") between the Company and The Bank of New York, as Trustee (the
"Trustee").

     As an inducement to the Initial Purchasers to enter into the Purchase
Agreement and in satisfaction of a condition to the Initial Purchasers'
obligations thereunder, the Company agrees with the Initial Purchasers, for the
benefit of the holders of the Notes (including, without limitation, the Initial
Purchasers) and the Exchange Notes (as defined below) (collectively, the
"Holders"), as follows:

     Section 1.  Registered Exchange Offer.  The Company shall prepare and file
                 -------------------------
with the U.S. Securities and Exchange Commission (the "SEC") a registration
statement (the "Exchange Offer Registration Statement") on an appropriate form
under the Securities Act of 1933, as amended (the "Securities Act"), with
respect to an offer (the "Registered Exchange Offer") to the Holders of Transfer
Restricted Notes (as defined in Section 6(d) hereof), who are not prohibited by
any law or policy of the SEC from participating in the Registered Exchange
Offer, to issue and deliver to such Holders, in exchange for the Notes of each
series, a like aggregate principal amount of notes of two series (the "Exchange
Notes") of the Company issued under the Indenture and identical in all material
respects to the Notes of each series that will be registered under the
Securities Act, except that (a) interest thereon shall accrue from the last date
on which interest has been paid on the Notes or, if no such interest has been
paid, from the date of original issue of the Notes and (b) they will not contain
terms with respect to transfer restrictions under the Securities Act.  The
Company shall use its reasonable best efforts to cause the Exchange
<PAGE>

Offer Registration Statement to become effective under the Securities Act on or
prior to 220 days after the date of original issue of the Notes and shall keep
the Exchange Offer Registration Statement effective for not less than 30 days
(or longer, if required by applicable law) after the date on which notice of the
Registered Exchange Offer is mailed to the Holders (that period being called the
"Exchange Offer Registration Period").

     If the Company effects the Registered Exchange Offer, the Company will be
entitled to close the Registered Exchange Offer at the close of business on the
30th day after the commencement thereof if the Company has accepted all the
Notes validly tendered by such 30th day in accordance with the terms of the
Registered Exchange Offer.

     Following the declaration of the effectiveness of the Exchange Offer
Registration Statement, the Company shall promptly commence the Registered
Exchange Offer, it being the objective of the Registered Exchange Offer to
enable each Holder of Transfer Restricted Notes electing to exchange those
Transfer Restricted Notes for Exchange Notes (assuming that such Holder is not
an affiliate of the Company within the meaning of the Securities Act, acquires
the Exchange Notes in the ordinary course of that Holder's business and has no
arrangement with any person to participate in the distribution of the Exchange
Notes, and is not prohibited by any law or policy of the SEC from participating
in the Registered Exchange Offer) to trade those Exchange Notes from and after
their receipt without any limitations or restrictions under the Securities Act
and without material restrictions under the securities laws of the several
states of the United States.  In connection with the Registered Exchange Offer,
the Company shall use its reasonable best efforts to consummate the Registered
Exchange Offer and shall comply with the applicable requirements of the
Securities Exchange Act of 1934, as amended (the "Exchange Act"), and other
applicable laws and regulations in connection with the Registered Exchange
Offer.

     The Company acknowledges that, pursuant to current interpretations by the
SEC's staff of Section 5 of the Securities Act, in the absence of an applicable
exemption therefrom, (a) each Holder that is a broker-dealer electing to
exchange Notes, acquired for its own account as a result of market-making
activities or other trading activities, for Exchange Notes (an "Exchanging
Dealer"), is required to deliver a prospectus containing the information set
forth in Annex A hereto on the cover, in Annex B hereto in the "Exchange Offer
Procedures" section and the "Purpose of the Exchange Offer" section, and in
Annex C hereto in the "Plan of Distribution" section, in connection with a sale
of any such Exchange Notes received by that Exchanging Dealer pursuant to the
Registered Exchange Offer, and (b) if the Initial Purchasers are permitted under
applicable law and applicable policies of the SEC to and elect to sell Exchange
Notes acquired in exchange for Notes constituting any portion of an unsold
allotment, they are required to deliver a prospectus containing the information
required by Item 507 or 508 of Regulation S-K under the Securities Act, as
applicable, in connection with that sale.

     The Company shall include in the prospectus contained in the Exchange Offer
Registration Statement a section titled "Plan of Distribution," reasonably
acceptable to the Initial Purchasers, that contains a summary statement of the
positions taken or policies made by the staff of the SEC with respect to the
potential "underwriter" status of any broker-dealer that is the beneficial owner
(as defined in Rule 13d-3 under the Exchange Act) of Exchange Notes received by
that broker-dealer in the Registered Exchange Offer (a "Participating Broker-
Dealer"),

                                       2
<PAGE>

whether those positions or policies have been publicly disseminated by the staff
of the SEC or, in the reasonable judgment of the Initial Purchasers based on
advice of counsel (which may be in-house counsel), represent the prevailing
views of the staff of the SEC.

     The Company shall use its reasonable best efforts to keep the Exchange
Offer Registration Statement effective and shall amend and supplement the
prospectus contained therein, in order to permit that prospectus to be lawfully
delivered by the Initial Purchasers and all Exchanging Dealers subject to the
prospectus delivery requirements of the Securities Act, and shall make that
prospectus available to the Initial Purchasers and those Exchanging Dealers for
such period of time after the consummation of the Registered Exchange Offer as
those persons must comply with those requirements in order to resell the
Exchange Notes.

     The Company shall make available for a period of 270 days after the
consummation of the Registered Exchange Offer a copy of the prospectus, and any
amendment or supplement thereto, forming part of the Exchange Offer Registration
Statement, to any broker-dealer for use in connection with any resale of any
Exchange Notes.  The Notes and the Exchange Notes are herein collectively called
the "Securities."

     In connection with the Registered Exchange Offer, the Company shall:

          (a)  mail to each Holder a copy of the prospectus forming part of the
     Exchange Offer Registration Statement, together with an appropriate letter
     of transmittal and related documents;

          (b)  keep the Registered Exchange Offer open for not less than 30 days
     (or longer, if required by applicable law) after the date notice thereof is
     mailed to the Holders;

          (c)  utilize the services of a depositary for the Registered Exchange
     Offer with an address in the Borough of Manhattan, The City of New York,
     which may be the Trustee or an affiliate of the Trustee;

          (d)  permit Holders to withdraw tendered Notes at any time prior to
     the close of business, New York time, on the last business day on which the
     Registered Exchange Offer remains open; and

          (e)  otherwise comply in all material respects with all applicable
     laws in effecting the Registered Exchange Offer.

     As soon as practicable after the close of the Registered Exchange Offer,
the Company shall:

               (i)   accept for exchange all the Notes validly tendered and not
     withdrawn pursuant to the Registered Exchange Offer;

               (ii)  deliver, or cause to be delivered, to the Trustee for
     cancellation all the Notes so accepted for exchange; and

                                       3
<PAGE>

               (iii) issue, and cause the Trustee to authenticate and deliver
     promptly to each Holder of the Notes, Exchange Notes, equal in principal
     amount to the Notes of each series held by that Holder so accepted for
     exchange.

     The Exchange Notes will not be subject to the restrictive legend set forth
on the Transfer Restricted Notes or the transfer restrictions (other than in
respect of minimum denominations) or bear Additional Interest other than as
provided in Section 6(a)(iii) herein.  The Indenture will provide that the Notes
and the Exchange Notes will vote and consent together on all matters as one
class and not as separate classes on any matter.

     Interest on each Exchange Note issued pursuant to the Registered Exchange
Offer will accrue from the last interest payment date on which interest was paid
on the Notes surrendered in exchange therefor or, if no interest has been paid
on those Notes, from the date of original issue of those Notes.

     The Registered Exchange Offer shall not be subject to any conditions, other
than that the Registered Exchange Offer shall not violate applicable law or any
applicable interpretation of the staff of the SEC and as provided in the next
sentence.  Each Holder participating in the Registered Exchange Offer will be
required to represent to the Company at the time of the consummation of the
Registered Exchange Offer:

          (a)  that any Exchange Note received by that Holder will be acquired
     in the ordinary course of business;

          (b)  that the Holder will have no arrangement or understanding with
     any person to participate in the distribution of the Notes or the Exchange
     Notes within the meaning of the Securities Act;

          (c)  that the Holder is not an "affiliate," as defined in Rule 405 of
     the Securities Act, of the Company or, if it is an affiliate, that Holder
     will comply with the registration and prospectus delivery requirements of
     the Securities Act to the extent applicable;

          (d)  if that Holder is not a broker-dealer, that it is not engaged in,
     and does not intend to engage in, any distribution of the Exchange Notes;
     and

          (e)  if that Holder is a broker-dealer, that it will receive Exchange
     Notes for its own account in exchange for Notes that were acquired as a
     result of market-making activities or other trading activities and that it
     will deliver a prospectus in connection with any resale of those Exchange
     Notes.

     Notwithstanding any other provision hereof, the Company will ensure that
(a) any Exchange Offer Registration Statement and any amendment thereto and any
prospectus forming part thereof and any supplement thereto complies in all
material respects with the Securities Act and the rules and regulations
thereunder, (b) any Exchange Offer Registration Statement and any amendment
thereto will not, when it becomes effective, contain an untrue statement of a
material fact or omit to state a material fact required to be stated therein or
necessary to make the statements therein not misleading, and (c) any prospectus
forming part of any Exchange Offer

                                       4
<PAGE>

Registration Statement, and any supplement to that prospectus, at the time of
issuance will not include an untrue statement of a material fact or omit to
state a material fact required to be stated therein or necessary in order to
make the statements therein, in light of the circumstances under which they were
made, not misleading; provided, however, that with respect to clauses (b) and
(c), the Company will not be liable to any Holder or Initial Purchaser for
written information relating to such Holder or Initial Purchaser furnished to
the Company by or on behalf of such Holder or Initial Purchaser specifically for
inclusion therein.

     Section 2.  Shelf Registration.  If (a) the Company determines that a
                 ------------------
Registered Exchange Offer, as contemplated by Section 1 hereof, is not available
or may not be consummated as soon as practicable after the last date the
Registered Exchange Offer is open because it would violate applicable law or the
applicable interpretations of the staff of the SEC, (b) the Exchange Offer
Registration Statement is not effective on or prior to 220 days after the date
of original issue of the Transfer Restricted Notes, (c) the Registered Exchange
Offer is not consummated on or prior to 270 days after the date of original
issue of the Transfer Restricted Notes, (d) the Initial Purchasers of the
Transfer Restricted Notes so request with respect to the Transfer Restricted
Notes not eligible to be exchanged for Exchange Notes in the Registered Exchange
Offer and held by them following consummation of the Registered Exchange Offer,
or (e) any Holder (other than an Exchanging Dealer) is not eligible to
participate in the Registered Exchange Offer under applicable law or applicable
policies of the SEC, or any Holder (other than an Exchanging Dealer) that
participates in the Registered Exchange Offer does not receive freely tradeable
Exchange Notes on the date of the exchange for validly tendered (and not
withdrawn) Transfer Restricted Notes:

                 (i)  The Company shall use its reasonable best efforts to
     prepare and file, as promptly as practicable, with the SEC and thereafter
     to cause to be declared effective a registration statement (the "Shelf
     Registration Statement" and, together with the Exchange Offer Registration
     Statement, a "Registration Statement") on an appropriate form under the
     Securities Act relating to the offer and sale of the Transfer Restricted
     Notes by the Holders thereof from time to time in accordance with the
     methods of distribution set forth in the Shelf Registration Statement and
     Rule 415 under the Securities Act (hereinafter, the "Shelf Registration"),
     but no Holder (other than the Initial Purchasers) is entitled to have any
     Transfer Restricted Notes held by it covered by that Shelf Registration
     Statement unless that Holder agrees in writing to be bound by all the
     provisions of this Agreement applicable to that Holder; and provided,
     however, that with respect to Exchange Notes which are attributable to
     Notes constituting any portion of an unsold allotment held by an Initial
     Purchaser, the Company may, if permitted by current interpretations of the
     SEC's staff and, in the opinion of the Company's counsel, sufficient to
     cause the Exchange Notes to be freely tradeable by such Initial Purchaser,
     file a post-effective amendment to the Exchange Offer Registration
     Statement containing the information required by Items 507 and 508 of
     Regulation S-K, as applicable, in satisfaction of its obligations under
     this subsection with respect thereto, and any such Exchange Offer
     Registration Statement, as so amended, shall be referred to herein as, and
     governed by the provisions herein applicable to, a Shelf Registration
     Statement.

                 (ii) The Company shall use all reasonable efforts to keep the
     Shelf Registration Statement continuously effective in order to permit the
     prospectus included

                                       5
<PAGE>

     therein to be lawfully delivered by the Holders of the relevant Securities,
     until the earlier of (A) the end of the period referred to in Rule 144(k)
     under the Securities Act after the original issue date of the Notes expires
     (or the end of such longer period as may result from an extension pursuant
     to Section 3(j) below), provided that, if this clause (A) is relied upon,
     counsel to the Company shall have delivered to Lehman Brothers Inc., an
     opinion to the effect that the Notes included in such Shelf Registration
     Statement will thereafter be freely tradeable by the Holders thereof
     without restriction, and (B) the date on which all the Securities covered
     by the Shelf Registration Statement have been sold pursuant thereto. Such
     period is hereinafter referred to as the "Shelf Registration Period."

               (iii)  Notwithstanding any provision of this Agreement to the
contrary, the Company shall cause the Shelf Registration Statement and the
related prospectus and any amendment or supplement thereto, as of the effective
date of the Shelf Registration Statement, amendment or supplement, (A) to comply
in all material respects with the applicable requirements of the Securities Act
and the rules and regulations of the SEC, (B) not to contain any untrue
statement of a material fact or omit to state a material fact required to be
stated therein or necessary in order to make the statements therein not
misleading; provided, however, that with respect to clause (B), the Company will
not be liable to any Holder or Initial Purchaser for written information
relating to such Holder or Initial Purchaser furnished to the Company by or on
behalf of such Holder or Initial Purchaser specifically for inclusion therein
and (C) not to relate to any securities other than the Transfer Restricted
Notes.

     Section 3.  Registration Procedures.  In connection with any Shelf
                 -----------------------
Registration contemplated by Section 2 hereof and, to the extent applicable, any
Registered Exchange Offer contemplated by Section 1 hereof, the following
provisions shall apply:

          (a)  The Company shall (i) furnish to the Initial Purchasers, prior to
the filing thereof with the SEC, a copy of the Registration Statement and each
amendment thereof and each supplement, if any, to the prospectus included
therein and shall not file any such Registration Statement or amendment thereto
or any prospectus or any supplement thereto (including any document that, upon
filing, would be incorporated or deemed to be incorporated by reference therein
and any amendment to any such document other than documents required to be filed
pursuant to the Exchange Act) to which the Initial Purchasers shall reasonably
object in writing, except for any Registration Statement or amendment thereto or
prospectus or supplement thereto (a copy of which has been previously furnished
to the Initial Purchasers and their counsel (and, in the case of a Shelf
Registration Statement, the Holders and their counsel)) which counsel to the
Company has advised the Company in writing is required to be filed,
notwithstanding any such objection, in order to comply with applicable law, (ii)
include information substantially to the effect set forth (A) in Annex A hereto
on the cover of the prospectus forming a part of the Exchange Offer Registration
Statement, (B) in Annex B hereto in the "Exchange Offer Procedures" section and
the "Purpose of the Exchange Offer" section of such prospectus, (C) in Annex C
hereto in the "Plan of Distribution" section of such prospectus, (iii) include
the information set forth in Annex D hereto in the Letter of Transmittal
delivered in connection with the Registered Exchange Offer, (iv) to the extent
required by law or interpretation of the staff of the SEC, if requested by the
Initial Purchasers, include the information required by Item 507 or 508 of
Regulation S-K under the Securities Act, as

                                       6
<PAGE>

applicable, in the prospectus forming a part of the Exchange Offer Registration
Statement, and (v) to the extent required by law or interpretation of the staff
of the SEC, in the case of a Shelf Registration Statement, include the names of
the Holders who propose to sell Securities pursuant to the Shelf Registration
Statement as selling securityholders.

          (b)  The Company shall notify promptly the Initial Purchasers, the
Holders and any Participating Broker-Dealer from whom the Company has received
prior written notice stating that it will be a Participating Broker-Dealer in
the Registered Exchange Offer (which notice pursuant to clauses (ii) through (v)
hereof shall be accompanied by an instruction to suspend the use of the
prospectus until any requisite changes have been made) and, if requested by the
Initial Purchasers, the Holders or any such Participating Broker-Dealer, confirm
such notice in writing:

               (i)   when the Registration Statement or any amendment thereto
     has been filed with the SEC and when the Registration Statement or any
     post-effective amendment thereto has become effective;

               (ii)  of any request by the SEC for an amendment or supplement to
     the Registration Statement or the prospectus included therein or for
     additional information;

               (iii) of the issuance by the SEC of any stop order suspending the
     effectiveness of the Registration Statement or the initiation of any
     proceeding for that purpose;

               (iv)  of the receipt by the Company or its legal counsel of any
     notification with respect to the suspension of the qualification of the
     Securities for sale in any jurisdiction or the initiation or threatening of
     any proceeding for that purpose;

               (v)   of the happening of any event that requires the Company to
     make changes in the Registration Statement or the prospectus in order that
     the Registration Statement or the prospectus does not contain an untrue
     statement of a material fact or omit to state a material fact required to
     be stated therein or necessary to make the statements therein not
     misleading; and

               (vi)  of any determination by the Company that a post-effective
     amendment to a Registration Statement would be appropriate.

          (c)  The Company shall make every reasonable effort to prevent the
issuance, and if issued to obtain the withdrawal at the earliest possible time,
of any order suspending the effectiveness of the Registration Statement and
shall provide prompt written notice to the Initial Purchasers and each Holder of
the withdrawal of any such order.

          (d)  The Company shall furnish to each Holder of Securities included
in the Shelf Registration, without charge, at least one conformed copy of the
Shelf Registration Statement and any post-effective amendment thereto, including
financial statements and schedules (without documents incorporated therein by
reference or exhibits thereto, unless a Holder so requests in writing).

                                       7
<PAGE>

          (e)  The Company shall deliver to the Initial Purchasers, and to any
other Holder that so requests, without charge, at least one conformed copy of
the Exchange Offer Registration Statement and any post-effective amendment
thereto, including financial statements and schedules (without documents
incorporated therein by reference or exhibits thereto, unless any such Holder or
the Initial Purchasers so request in writing).

          (f)  The Company shall deliver to each Holder of Securities included
in the Shelf Registration, without charge, as many copies of the prospectus
(including each preliminary prospectus) included in the Shelf Registration
Statement and any amendment or supplement thereto as that Holder may reasonably
request during the Shelf Registration Period. The Company consents, subject to
the provisions of this Agreement, to the use of the prospectus or any amendment
or supplement thereto by each of the selling Holders of the Securities in
connection with the offering and sale of the Securities covered by, and as
contemplated by, the prospectus, or any amendment or supplement thereto,
included in the Shelf Registration Statement.

          (g)  The Company shall deliver to each Initial Purchaser, any
Participating Broker-Dealer and any Exchanging Dealer, without charge, as many
copies of the final prospectus included in the Exchange Offer Registration
Statement and any amendment or supplement thereto as that person or entity may
reasonably request. The Company consents, subject to the provisions of this
Agreement, to the use of the prospectus or any amendment or supplement thereto
by the Initial Purchasers, if necessary, any Participating Broker-Dealer and any
Exchanging Dealer and such other persons as may be required to deliver a
prospectus following the Registered Exchange Offer in connection with the
offering and sale of the Exchange Notes covered by the prospectus, or any
amendment or supplement thereto, included in the Exchange Offer Registration
Statement, but no such person or entity is authorized by the Company to deliver
and no such person or entity shall deliver any such prospectus more than 270
days following the consummation of the Registered Exchange Offer, in connection
with any resale contemplated by this paragraph.

          (h)  Prior to any public offering of Securities pursuant to any
Registration Statement, the Company shall use all reasonable efforts to register
or qualify or cooperate with the Holders of the Securities included therein and
their respective counsel in connection with the registration or qualification of
the Securities for offer and sale under the securities or Blue Sky laws of such
states of the United States as any Holder of the Securities reasonably requests
in writing and shall do any and all other acts or things necessary or advisable
to enable that Holder to offer and sell in such jurisdictions the Securities
covered by that Registration Statement owned by that Holder, but the Company is
not required to (i) qualify generally or as a foreign corporation to do business
in any jurisdiction where it is not then so qualified or (ii) take any action
which would subject it to general service of process or to taxation in any
jurisdiction where it is not then so subject.

          (i)  The Company shall cooperate with the Holders of the Securities to
facilitate the timely preparation and delivery of certificates representing the
Securities to be sold pursuant to any Shelf Registration Statement free of any
restrictive legend and in such denominations (consistent with the provisions of
the Indenture and as described in the

                                       8
<PAGE>

prospectus) and registered in such names as the Holders may request at least two
business days prior to closing of any sale of the Securities pursuant to such
Shelf Registration Statement.

          (j)  If any event contemplated by paragraphs (ii) through (vi) of
Section 3(b) above occurs during the period in which the Company is required to
maintain an effective Registration Statement, the Company shall promptly prepare
and file a post-effective amendment to the Registration Statement or a
supplement to the related prospectus and any other required document so that, as
thereafter delivered to Holders of the Notes or purchasers of Securities, the
prospectus will not contain an untrue statement of a material fact or omit to
state any material fact required to be stated therein or necessary to make the
statements therein, in light of the circumstances under which they were made,
not misleading. If the Company notifies the Initial Purchasers, the Holders of
the Securities and any known Participating Broker-Dealer in accordance with
paragraphs (ii) through (vi) of Section 3(b) above to suspend the use of the
prospectus until any requisite changes to the prospectus have been made, then
the Initial Purchasers, the Holders of the Securities and any such Participating
Broker-Dealer shall suspend use of that prospectus until the Company has amended
or supplemented the prospectus to correct any misstatement or omission, and the
period of effectiveness of the Shelf Registration Statement provided for in
Section 2(b) above shall be extended by the number of days from and including
the date of the giving of that notice to and including the date when the Initial
Purchasers, the Holders of the Securities and any known Participating Broker-
Dealer shall have received that amended or supplemented prospectus pursuant to
this Section 3(j). Each Initial Purchaser, Holder and Participating Broker-
Dealer agrees that on receipt of any such notice from the Company it will not
distribute copies of the prospectus that are the subject of that notice and will
retain those copies in its files.

          (k)  Not later than the effective date of the applicable Registration
Statement, the Company will obtain a CUSIP number for each series of the
Transfer Restricted Notes or the Exchange Notes, as the case may be, and provide
the Trustee with printed certificates for the Notes or the Exchange Notes, as
the case may be, in a form eligible for deposit with The Depository Trust
Company.

          (l)  The Company will comply with all rules and regulations of the SEC
to the extent and so long as they are applicable to the Registered Exchange
Offer or the Shelf Registration and will make generally available to its
security holders (or otherwise provide in accordance with Section 11(a) of the
Securities Act) an earnings statement satisfying the provisions of Section 11(a)
of the Securities Act, no later than 45 days after the end of the 12-month
period (or 90 days, if that period is a fiscal year) that begins with the first
month of the Company's first fiscal quarter commencing after the effective date
of the Registration Statement, which statement will cover that 12-month period.

          (m)  The Company shall cause the Indenture to be qualified under the
Trust Indenture Act of 1939, as amended, in a timely manner and to contain any
changes that are necessary for that qualification. If that qualification would
require the appointment of a new trustee under the Indenture, the Company shall
appoint a new trustee thereunder pursuant to the applicable provisions thereof.

                                       9
<PAGE>

          (n)  The Company will require each Holder of Securities to be sold
pursuant to any Shelf Registration Statement to furnish to the Company such
information regarding that Holder and the distribution of the Securities as the
Company may from time to time reasonably request for inclusion in the Shelf
Registration Statement, and to provide comments on the Shelf Registration
Statement, and the Company may exclude from that registration the Securities of
any Holder that unreasonably fails to furnish that information and those
comments within a reasonable time after receiving that request.

          (o)  In the case of any Shelf Registration, the Company shall enter
into such customary agreements (including, if requested, an underwriting
agreement in customary form) and take all such other action, if any, as the
Holders of a majority of the Securities being sold shall reasonably request in
order to facilitate the disposition of the Securities pursuant to that Shelf
Registration; provided that the Company shall have no obligation to pay fees and
expenses of counsel to the underwriters and underwriting discounts and
commissions and transfer taxes, if any, relating to the sale or disposition of
Securities by a Holder.

          (p)  In the case of any Shelf Registration, the Company shall make
available for inspection by a single representative of the Holders of Securities
being sold, one firm of legal counsel and an accountant or a single accounting
firm retained by those Holders, in a manner designed to permit underwriters to
satisfy their due diligence investigation under the Securities Act, all
financial and other records, pertinent corporate documents and properties of the
Company customarily inspected by underwriters in primary underwritten offerings
and shall cause the officers, directors and employees of the Company and its
subsidiaries to supply all information reasonably requested by, and customarily
supplied in connection with primary underwritten offerings to, any such
representative, attorney or accountant in connection with that registration, but
any records, information or documents that are designated by the Company as
confidential at the time of delivery thereof shall be kept confidential by those
persons, unless (i) those records, information or documents are in the public
domain or otherwise publicly available, (ii) disclosure of those records,
information or documents is required by a court or administrative order or (iii)
disclosure of those records, information or documents, in the written opinion of
counsel to those persons, is otherwise required by law (including, without
limitation, pursuant to the Securities Act).

          (q)  In the case of any Shelf Registration, the Company, if requested
by any Holder of Securities covered thereby, shall: (i) cause its counsel to
deliver an opinion and updates thereof relating to the Securities in customary
form addressed to the selling Holder and the managing underwriters, if any,
covering matters customarily covered in opinions requested in underwritten
offerings; (ii) cause its officers to execute and deliver such documents and
certificates and updates thereof as may be reasonably requested by any
underwriter of the applicable Securities, and which are customarily delivered in
underwritten offerings, to evidence the continued validity of the
representations and warranties of the Company made pursuant to, and to evidence
compliance with any customary conditions contained in, an underwriting agreement
and to provide indemnification and contribution on terms no less favorable than
those set forth in Section 5 hereof with respect to all parties to be
indemnified (including, without limitation, selling Holders and underwriters);
and (iii) cause its independent public accountants to provide to the selling
Holders of the applicable Securities (and any underwriter therefor) a comfort
letter in customary form and covering matters of the type customarily covered in

                                       10
<PAGE>

comfort letters in connection with primary underwritten offerings, subject to
receipt of appropriate documentation as contemplated, and only if permitted, by
Statement of Auditing Standards No. 72.

          (r)  (i) Upon consummation of a Registered Exchange Offer, the Company
shall, if requested by the Trustee, obtain an opinion of counsel to the Company
addressed to the Trustee for the benefit of all Holders participating in the
Registered Exchange Offer and which includes an opinion that (A) the Company has
duly authorized, executed and delivered the Exchange Notes and (B) each of the
Exchange Notes constitutes a legal, valid and binding obligation of the Company,
enforceable in accordance with its terms (with customary exceptions);

               (ii) In the case of any Exchange Offer Registration Statement,
     the Company shall deliver to the Initial Purchasers or to another
     representative of the Participating Broker-Dealers, if requested by any
     such Initial Purchasers or such other representative of the Participating
     Broker-Dealers, on behalf of the Participating Broker-Dealers, upon
     consummation of the Exchange Offer (A) an opinion of counsel in form and
     substance reasonably satisfactory to the Initial Purchasers or such other
     representative of the Participating Broker-Dealers, covering matters
     customarily covered in opinions requested in connection with Exchange Offer
     Registration Statements and such other matters as may be reasonably
     requested, (B) an officer's certificate containing certifications and
     updates thereof substantially similar to those set forth in certificates
     delivered pursuant to Section 7 of the Note Purchase Agreement and such
     additional certifications as are customarily delivered in primary
     underwritten offerings, and (C) a comfort letter, in customary form and
     covering matters of the type customarily covered in comfort letters in
     connection with primary underwritten offerings, subject to receipt of
     appropriate documentation as contemplated, and only if permitted, by
     Statement on Auditing Standards No. 72.

          (s)  If a Registered Exchange Offer is to be consummated, upon
delivery of the Notes by Holders to the Company (or to any other Person
designated by the Company) in exchange for the Exchange Notes, the Company shall
mark, or caused to be marked, on the Notes so exchanged that those Notes are
being canceled in exchange for the Exchange Notes, and in no event shall the
Notes be marked as paid or otherwise satisfied.

          (t)  If any broker-dealer registered under the Exchange Act
underwrites any Securities or participates as a member of an underwriting
syndicate or selling group or "assists in the distribution" (within the meaning
of the Conduct Rules of the National Association of Securities Dealers, Inc.
("NASD")) thereof, whether as a Holder of those Securities or as an underwriter,
a placement or sales agent or a broker or dealer in respect thereof, or
otherwise, the Company shall assist such broker-dealer in complying with the
requirements of those Rules and By-Laws, including by (i) if those Rules,
including Rule 2720, shall so require, engaging a "qualified independent
underwriter" (as defined in Rule 2720) to participate in the preparation of the
Registration Statement relating to those Securities, to exercise usual standards
of due diligence in respect thereto and, if any portion of the offering
contemplated by that Registration Statement is an underwritten offering or is
made through a placement or sales agent, to recommend the yield of such
Securities, (ii) indemnifying any such qualified independent

                                       11
<PAGE>

underwriter to the extent of the indemnification of underwriters provided in
Section 5 hereof, and (iii) providing such information to that broker-dealer as
may be required in order for that broker-dealer to comply with the requirements
of the Conduct Rules of the NASD.

          (u)  The Company will be deemed not to have used its best efforts to
cause the Exchange Offer Registration Statement or a required Shelf
Registration, as the case may be, to become, or to remain, effective at the
requisite date or during the requisite period if the Company voluntarily takes
any action that would result in such Registration Statement not being declared
effective or in the Holders not being able to exchange or offer and sell their
securities during that period, unless such action by the Company is required by
law.

     Section 4.  Registration Expenses.  The Company shall pay all fees and
                 ---------------------
expenses incident to the performance of or compliance with this Agreement by the
Company including, without limitation:  (a) all SEC, stock exchange or NASD
registration and filing fees; (b) all fees and expenses incurred in connection
with compliance with state securities or Blue Sky laws (including reasonable
fees and disbursements of Winthrop, Stimson, Putnam & Roberts as counsel for any
underwriters or Holders in connection with Blue Sky qualification of any of the
Securities); (c) all out of pocket expenses of any persons retained by the
Company in connection with preparing or assisting in preparing, word processing,
printing and distributing any Registration Statement, any prospectus, any
amendment or supplement to either thereof, any underwriting agreement,
securities sales agreement or other document relating to the performance of and
compliance with this Agreement; (d) all rating agency fees; (e) the fees and
disbursements of counsel for the Company and, in the event of a Shelf
Registration, the reasonable fees and disbursements of Winthrop, Stimson, Putnam
& Roberts as counsel for the Holders and of the independent public accountants
of the Company, including the expense of any special audit or "cold comfort"
letter required by or incident to that performance and compliance, but excluding
fees and expenses of counsel to the underwriters and underwriting discounts and
commissions and transfer taxes, if any, relating to the sale or disposition of
Securities by a Holder and; (f) the fees and expenses of the Trustee, and any
paying agent, exchange agent or custodian.

     Section 5.  Indemnification.  (a)  The Company agrees to indemnify and hold
                 ---------------
harmless each Holder of Securities, any Participating Broker-Dealer, and each
person, if any, who controls that Holder or Participating Broker-Dealer within
the meaning of either Section 15 of the Securities Act or Section 20 of the
Exchange Act, or is under common control with, or is controlled by, that Holder
or Participating Broker-Dealer, from and against any and all losses, claims,
damages, liabilities or expenses, as and when incurred, (including, without
limitation, any legal or other expenses reasonably incurred in connection with
defending or investigating any such action or claim) caused by any untrue
statement or alleged untrue statement of a material fact contained in a
Registration Statement or the related prospectus (as amended or supplemented if
the Company shall have furnished any amendment or supplement thereto), or caused
by any omission or alleged omission to state therein a material fact required to
be stated therein or necessary to make the statements therein not misleading,
except insofar as such losses, claims, damages or liabilities are caused by any
such untrue statement or omission or alleged untrue statement or omission based
on information relating to that Holder or Participating Broker-Dealer furnished
to the Company in writing by that Holder or Participating Broker-Dealer
expressly for use therein, but the foregoing indemnity in respect of any
prospectus will

                                       12
<PAGE>

not inure to the benefit of any Holder or Participating Broker-Dealer from whom
the person asserting any such losses, claims, damages or liabilities purchased
Securities, or any person controlling or affiliated with that Holder or
Participating Broker-Dealer, if a copy of an amendment or supplement to the
prospectus (furnished by the Company on a timely basis) was not sent or given by
or on behalf of that Holder or Participating Broker-Dealer to that person, if
required by law so to have been delivered, at or prior to the written
confirmation of the sale of the Securities to that person, and if such amendment
or supplement would have cured the defect giving rise to that loss, claim,
damage or liability.

          (b)  Each Participating Broker-Dealer and Holder of Securities,
severally and not jointly, agrees to indemnify and hold harmless the Company,
other selling Holders and Participating Broker-Dealers, directors of the
Company, the officers of the Company who sign a Registration Statement and each
person, if any, who controls the Company or any selling Holder or Participating
Broker-Dealer, within the meaning of either Section 15 of the Securities Act or
Section 20 of the Exchange Act, to the same extent as the foregoing indemnity
from the Company to that Holder or Participating Broker-Dealer, but only with
reference to information relating to that Holder or Participating Broker-Dealer
furnished to the Company in writing by that Holder or Participating Broker-
Dealer expressly for use in a Registration Statement, any preliminary
prospectus, prospectus or any amendment or supplement to any thereof.

          (c)  If any proceeding (including any governmental investigation) is
instituted involving any person in respect of which indemnity may be sought
pursuant to either paragraph (a) or (b) above, that person (the "indemnified
party") shall promptly notify the person against whom that indemnity may be
sought (the "indemnifying party") in writing and the indemnifying party, upon
request of the indemnified party, shall retain counsel reasonably satisfactory
to the indemnified party to represent the indemnified party and any others the
indemnifying party may designate in that proceeding and shall pay the fees and
expenses of that counsel related to that proceeding; but the omission so to
notify the indemnifying party shall not relieve the indemnifying party from any
liability which it may have to any indemnified party on account of this
indemnity (except to the extent that the indemnifying party is materially
prejudiced by such failure) or otherwise. In any such proceeding, any
indemnified party may retain its own counsel, but the fees and expenses of that
counsel will be at the expense of that indemnified party unless (i) the
indemnifying party and the indemnified party shall have mutually agreed to the
retention of that counsel, (ii) the indemnifying party does not assume the
defense of such proceeding in a timely manner or (iii) the named parties to any
such proceeding (including any impleaded parties) include both the indemnifying
party and the indemnified party and the indemnified party reasonably objects to
such assumption on the ground that there may be legal defenses available to it
that are different from or in addition to those available to the indemnifying
party or another indemnifying party. It is understood that the indemnifying
party shall not, in respect of the legal expenses of any indemnified party in
connection with any proceeding or related proceedings in the same jurisdiction,
be liable for the fees and expenses of more than one separate firm (in addition
to any local counsel) for all such indemnified parties and that all such fees
and expenses shall be reimbursed as they are incurred. If an indemnified party
includes (x) the Initial Purchasers or such controlling persons of the Initial
Purchasers, that firm will be designated in writing by Lehman Brothers Inc.; or
(y) Holders of Securities (other than the Initial Purchasers) or controlling
persons of those Holders, that firm will be designated in writing by the Holders
of a majority in aggregate principal amount of those Securities. In all other
cases, the Company

                                       13
<PAGE>

will designate that firm. The indemnifying party will not be liable for any
settlement of any proceeding effected without its written consent, but if
settled with that consent or if there be a final judgment for the plaintiff, the
indemnifying party agrees to indemnify the indemnified party from and against
any loss or liability by reason of that settlement or judgment. Notwithstanding
the foregoing sentence, if at any time an indemnified party has requested an
indemnifying party to reimburse the indemnified party for fees and expenses of
counsel as contemplated by the second and third sentences of this paragraph, the
indemnifying party agrees that it will be liable for any settlement of any
proceeding effected without its written consent if (i) that settlement is
entered into more than 45 days after receipt by the indemnifying party of the
aforesaid request and (ii) the indemnifying party shall not have reimbursed the
indemnified party in accordance with that request prior to the date of that
settlement. No indemnifying party may, without the prior written consent of the
indemnified party, effect any settlement or compromise of, or consent to the
entry of a judgment with respect to, any pending or threatened proceeding in
respect of which indemnity could have been sought hereunder by that indemnified
party, unless that settlement, compromise or judgment (i) includes an
unconditional release of that indemnified party from all liability on claims
that are the subject matter of that proceeding and (ii) does not include a
statement as to, or an admission of, fault, culpability or a failure to act, by
or on behalf of any indemnified party.

          (d)  To the extent the indemnification provided for in paragraph (a)
or (b) of this Section 5 is unavailable to an indemnified party or insufficient
in respect of any losses, claims, damages, liabilities or expenses referred to
therein, then each indemnifying party shall contribute to the amount paid or
payable by such indemnified party as a result of such losses, claims, damages,
liabilities or expenses (or actions in respect thereof) in such proportion as is
appropriate to reflect the relative benefits received by the Company on the one
hand and each Participating Broker-Dealer and Holder on the other from the
offering of the Notes. If, however, the allocation provided by the immediately
preceding sentence is not permitted by applicable law, then each indemnifying
party shall contribute to such amount paid or payable by such indemnified party
in such proportion as is appropriate to reflect not only such relative benefits
but also the relative fault of the Company on the one hand and each
Participating Broker-Dealer and Holder on the other in connection with the
statements or omissions which resulted in such losses, claims, damages,
liabilities or expenses (or actions in respect thereof), as well as any other
relevant equitable considerations. The relative benefits received by the Company
on the one hand and each Participating Broker-Dealer and Holder on the other
shall be deemed to be in the same proportion as the total net proceeds from the
offering (before deducting expenses) received by the Company and the total fees
received by each Participating Broker-Dealer and Holder in connection with the
offering of the Notes bear to the total price of the Notes as set forth on the
cover page of the Offering Circular. The relative fault shall be determined by
reference to, among other things, whether the untrue or alleged untrue statement
of a material fact or the omission or alleged omission to state a material fact
relates to information supplied by the Company on the one hand or each
Participating Broker-Dealer and Holder on the other and the parties' relative
intent, knowledge, access to information and opportunity to correct or prevent
such statement or omission. The Holders' and Participating Broker-Dealers'
respective obligations to contribute pursuant to this Section 5 are several in
proportion to the respective amount of Notes they have purchased, not joint.

                                       14
<PAGE>

          (e)  The Company, each Participating Broker-Dealer and each Holder
agree that it would not be just or equitable if contribution pursuant to this
Section 5 were determined by pro rata allocation or by any other method of
                             --------
allocation that does not take account of the equitable considerations referred
to in subsection (d) of this Section 5. The amount paid or payable by an
indemnified party as a result of the losses, claims, damages and liabilities
referred to in subsection (d) above is deemed to include, subject to the
limitations set forth above, any legal or other expenses reasonably incurred by
that indemnified party in connection with investigating or defending any such
action or claim. Notwithstanding the provisions of this Section 5, no Holder of
Securities is required to contribute any amount in excess of the amount by which
the total price at which the Securities sold by that Holder pursuant to a
Registration Statement were sold exceeds the amount of any damages that Holder
has otherwise been required to pay by reason of that untrue or alleged untrue
statement or omission or alleged omission. No person guilty of fraudulent
misrepresentation (within the meaning of Section 11(f) of the Securities Act) is
entitled to contribution from any person who was not guilty of such fraudulent
misrepresentation.

          (f)  The indemnity and contribution provisions contained in this
Section 5 will remain operative and in full force and effect regardless of (i)
any termination of this Agreement, (ii) any investigation made by or on behalf
of any Holder or Participating Broker-Dealer or any person controlling that
Holder or Participating Broker-Dealer or by or on behalf of the Company, their
respective officers or directors or any person controlling the Company, and
(iii) the sale of the Securities. The remedies provided for in this Section 5
are not exclusive and do not limit any rights or remedies that may otherwise be
available to any indemnified party at law or in equity.

     Section 6.  Additional Interest Under Certain Circumstances.  (a)
                 -----------------------------------------------
Additional interest (the "Additional Interest") with respect to the Securities
will be assessed as follows if any of the following events occurs (each event
identified in clause (i), (ii), (iii), (iv) or (v) below, an "Additional
Interest Event"):

               (i)   If the Exchange Offer Registration Period is not closed and
     all Transfer Restricted Notes properly tendered to the Company have not
     been exchanged for Exchange Notes on or prior to 270 days after the
     original issue date of the Notes; or

               (ii)  If, after the Exchange Offer Registration Statement is
     declared effective, such Exchange Offer Registration Statement thereafter
     ceases to be effective at any time during the required period specified
     within this Agreement; or

               (iii) If the Company ceases to maintain its status as a reporting
     company under the Exchange Act whether or not the SEC rules and regulations
     require the Company to maintain that status (unless the SEC will not accept
     the filing of the applicable reports); or

               (iv)  Whether or not the Registered Exchange Offer is
     consummated, any required Shelf Registration Statement is not filed as
     promptly as practicable, and in any event within 45 days, following the
     event giving rise to the requirement to file a Shelf Registration Statement
     in accordance with this Agreement; or

                                       15
<PAGE>

               (v)  If, after any Shelf Registration Statement is declared
     effective, (A) such Shelf Registration Statement thereafter ceases to be
     effective during the Shelf Registration Period; or (B) such Shelf
     Registration Statement or the related prospectus ceases to be usable in
     connection with resales of Transfer Restricted Notes during the Shelf
     Registration Period (except as permitted in paragraph (b) of this Section
     6) because either (1) any event occurs as a result of which the related
     prospectus forming part of such Shelf Registration Statement would include
     any untrue statement of a material fact or omit to state any material fact
     necessary to make the statements therein, in the light of the circumstances
     under which they were made not misleading, or (2) it shall be necessary to
     amend such Shelf Registration Statement, or supplement the related
     prospectus, to comply with the Securities Act or the Exchange Act or the
     respective rules thereunder.

          Additional Interest shall accrue on the Transfer Restricted Notes over
and above the interest set forth in the title of the applicable series of the
Notes from and including the date on which any such Additional Interest Event
shall occur to, but excluding, the date on which all such Additional Interest
Events have been cured or terminated, at a rate of 0.50% per annum and such
Additional Interest shall be payable in accordance with Section 6(c).  In the
event that more than one of the aforementioned Additional Interest Event occurs
at the same time, the maximum increase in the interest rate applicable to the
Notes shall be 0.50% per annum.

          (b)  An Additional Interest Event referred to in Section 6(a)(v) is
deemed not to be continuing in relation to a Shelf Registration Statement or the
related prospectus if (i) that Additional Interest Event has occurred solely as
a result of (x) the filing of a post-effective amendment to such Shelf
Registration Statement to incorporate annual audited financial information with
respect to the Company, when such post-effective amendment is not yet effective
and needs to be declared effective to permit Holders to use the related
prospectus or (y) the occurrence of other material events or developments with
respect to the Company or its Affiliates that would need to be described in such
Shelf Registration Statement or the related prospectus, and (ii) in the case of
clause (y), the Company is proceeding promptly and in good faith to amend or
supplement such Shelf Registration Statement and related prospectus to describe
those events or, in the case of material developments that the Company
determines in good faith must remain confidential for business reasons, the
Company is proceeding promptly and in good faith to take such steps as are
necessary so that those developments need no longer remain confidential, but in
any case, if any Additional Interest Event (including any referred to in clause
(x) or (y), above) continues for a period in excess of 45 days, Additional
Interest will be payable in accordance with the above paragraph from the day
following the last day of that 45-day period until the date on which that
Additional Interest Event is cured.

          (c)  Any Additional Interest payable will be payable on the regular
interest payment dates with respect to the Notes, in the same manner as the
manner in which regular interest is payable. The amount of Additional Interest
for any period will be determined by multiplying the applicable Additional
Interest rate by the principal amount of the Notes of the applicable series,
multiplied by a fraction, the numerator of which is the number of days that
Additional Interest rate was applicable during that period (determined on the
basis of a 360-day year comprised of twelve 30-day months), and the denominator
of which is 360.

                                       16
<PAGE>

          (d)  "Transfer Restricted Note" means each Note until: (i) the date on
which that Note has been exchanged by a person other than a broker-dealer for a
freely transferable Exchange Note in the Registered Exchange Offer; (ii)
following the exchange by a broker-dealer in the Registered Exchange Offer of a
Transfer Restricted Note for an Exchange Note, the date on which that Exchange
Note is sold to a purchaser who receives from that broker-dealer on or prior to
the date of that sale a copy of the prospectus constituting part of the Exchange
Offer Registration Statement; (iii) the date on which that Note has been
effectively registered under the Securities Act and disposed of in accordance
with the Shelf Registration Statement; or (iv) the date on which that Note is
distributed to the public pursuant to Rule 144 under the Securities Act or
becomes freely tradeable pursuant to Rule 144(k) under the Securities Act.

     Section 7.  Rules 144 and 144A.  The Company shall use its best efforts to
                 ------------------
file the reports required to be filed by it under the Securities Act and the
Exchange Act in a timely manner.  If at any time the Company is not required to
file those reports, it will, upon the request of any Holder of Transfer
Restricted Notes, make publicly available other information so long as is
necessary to permit sales of Securities pursuant to Rules 144 and 144A and
otherwise as required by the Indenture.  The Company covenants that it will take
such further action as any Holder of Transfer Restricted Notes may reasonably
request, all to the extent required from time to time to enable that Holder to
sell Transfer Restricted Notes without registration under the Securities Act
within the limitation of the exemptions provided by Rules 144 and 144A
(including the requirements of Rule 144A(d)(4)).  Upon request by an Initial
Purchaser, the Company will provide a copy of this Agreement to prospective
purchasers of Notes identified in writing to the Company by that Initial
Purchaser.  Upon the request of any Holder of Transfer Restricted Notes, the
Company shall deliver to that Holder a written statement as to whether it has
complied with those requirements.  Notwithstanding the foregoing, nothing in
this Section 7 requires the Company to register any of its securities under the
Exchange Act.

     Section 8.  Underwritten Registrations.  If any of the Transfer Restricted
                 --------------------------
Notes covered by any Shelf Registration are to be sold in an underwritten
offering, the investment banker or investment bankers and manager or managers
that will administer the offering ("Managing Underwriters") will be selected by
the Holders of a majority in aggregate principal amount of the Transfer
Restricted Notes included in that offering, but the Managing Underwriters must
be reasonably satisfactory to the Company.

     No person may participate in any underwritten registration hereunder unless
that person (a) agrees to sell that person's Transfer Restricted Notes on the
basis reasonably provided in any underwriting arrangements approved by the
persons entitled hereunder to approve those arrangements, and (b) completes and
executes all questionnaires, powers of attorney, indemnities, underwriting
agreements and other documents reasonably required under the terms of those
underwriting arrangements.

     Section 9.  Miscellaneous.  (a) Amendments and Waivers.  The provisions of
                 -------------       ----------------------
this Agreement may not be amended, modified or supplemented, and waivers or
consents to departures from the provisions hereof may not be given, except by
the Company and the written consent of the Holders of a majority in principal
amount of the Securities affected thereby; provided that no amendment,
modification or supplement with respect to Section 6 hereof shall be effective
as against any Holder unless such amendment, modification or supplement either
(i)

                                       17
<PAGE>

shall have no adverse effect on the Holder or (ii) such Holder shall have
consented to such amendment, modification or supplement.

          (b)  Notices.  All statements, requests, notices and agreements
               -------
hereunder shall be made in writing, and:

               (i)  if to the Initial Purchasers, shall be delivered or sent by
     mail, telex or facsimile transmission to Lehman Brothers Inc., 3 World
     Financial Center, New York, New York 10285, Attention: John Veech (Fax:
     212-526-4827), with a copy to Winthrop, Stimson, Putnam & Roberts, One
     Battery Park Plaza, New York, New York 10004-1490, Attention: David P.
     Falck, Esq. (Fax: 212-858-1500); and

               (ii) if to the Company, shall be delivered or sent by mail, telex
     or facsimile transmission to Ameren Energy Generating Company, One Ameren
     Plaza, 1901 Chouteau Avenue, P.O. Box 66149, MC 1300, St. Louis, Missouri
     63166-6149, Attention: General Counsel (Fax: 314-554-4014), with a copy to
     Jones, Day, Reavis & Pogue, 77 W. Wacker Drive, Chicago, Illinois 60601,
     Attention: William J. Harmon. (Fax: 312-782-8585).

All such notices and communications will be deemed to have been duly given:  (A)
at the time delivered by hand, if personally delivered; (B) three business days
after being deposited in the mail, postage prepaid, if mailed; (C) when receipt
is acknowledged by the recipient's facsimile machine operator, if sent by
facsimile transmission; or (D) on the day delivered, if sent by overnight air
courier guaranteeing next day delivery.

          (c)  No Inconsistent Agreements.  The Company has not, as of the date
               --------------------------
hereof, entered into, nor will it, on or after the date hereof, enter into, any
agreement with respect to the Securities that is inconsistent with the rights
granted to the Holders herein or that otherwise conflicts with this Agreement.

          (d)  Successors and Assigns.  This Agreement is binding on the Company
               ----------------------
and its successors and assigns.

          (e)  Counterparts.  This Agreement may be executed in any number of
               ------------
counterparts and by the parties hereto in separate counterparts, each of which
when so executed will constitute an original and all of which taken together
will constitute one and the same agreement.

          (f)  Governing Law.  This Agreement is governed by, and is to be
               -------------
construed in accordance with, the laws of the State of New York without regard
to principles of conflicts of law.

          (g)  Severability.  If any one or more of the provisions contained
               ------------
herein, or the application thereof in any circumstance, is held invalid, illegal
or unenforceable, the validity, legality and enforceability of any such
provision in every other respect and of the remaining provisions contained
herein is not affected or impaired thereby.

                                       18
<PAGE>

          (h)  Securities Held by the Company.  Whenever the consent or approval
               ------------------------------
of Holders of a specified percentage of principal amount of Securities is
required hereunder, Securities held by the Company or its affiliates will not be
counted in determining whether that consent or approval was given by the Holders
of that required percentage.

          (i)  Specific Performance.  Without limiting the remedies available to
               --------------------
the Holders, the Company acknowledges that any failure by it to comply with
their obligations under Section 1 or Section 2 hereof may result in material
irreparable injury to the Holder for which there is no adequate remedy at law,
that it would not be possible to measure damages for such failure precisely and
that, in the event of any such failure, any Holder may obtain such relief as is
necessary to enforce specifically the obligations of the Company.

                 [REMAINDER OF PAGE INTENTIONALLY LEFT BLANK]

                                       19
<PAGE>

     If the foregoing is in accordance with your understanding of our agreement,
please sign and return to the Company a counterpart hereof, whereupon this
instrument, along with all counterparts, will become a binding agreement between
the Initial Purchasers and the Company in accordance with its terms.

                                          Very truly yours,
                                          AMEREN ENERGY GENERATING
                                          COMPANY

                                          By:         /s/ Jerre E. Birdsong
                                             -----------------------------------
                                               Name:  Jerre E. Birdsong
                                               Title: Treasurer

Accepted as of the date hereof

Lehman Brothers Inc.
Chase Securities Inc.
Banc of America Securities, LLC
Banc One Capital Markets, Inc.
BNY Capital Markets, Inc.

By:  LEHMAN BROTHERS INC.

By:    /s/ Jane E. Hawkins
   -----------------------------
     Name:  Jane E. Hawkins
     Title: Vice President

                                       20
<PAGE>

                                                                         ANNEX A

     Each broker-dealer that receives Exchange Notes for its own account
pursuant to the Exchange Offer must acknowledge that it will deliver a
prospectus in connection with any resale of such Exchange Notes.  The Letter of
Transmittal states that by so acknowledging and by delivering a prospectus, a
broker-dealer will not be deemed to admit that it is an "underwriter" within the
meaning of the Securities Act.  This Prospectus, as it may be amended or
supplemented from time to time, may be used by a broker-dealer in connection
with resales of Exchange Notes received in exchange for Existing Notes where
such Existing Notes were acquired by such broker-dealer as a result of market-
making activities or other trading activities.  The Company has agreed that, for
a period of 270 days after the consummation of the Exchange Offer, it will make
this Prospectus available to any broker-dealer for use in connection with any
such resale.  See "Plan of Distribution".
<PAGE>

                                                                         ANNEX B

     Each broker-dealer that receives Exchange Notes for its own account in
exchange for Existing Notes, that were acquired by that broker-dealer as a
result of market-making activities or other trading activities, must acknowledge
that it will deliver a prospectus in connection with any resale of those
Exchange Notes.  See "Plan of Distribution."
<PAGE>

                                                                         ANNEX C

     Each broker-dealer that receives Exchange Notes for its own account
pursuant to the Exchange Offer must acknowledge that it will deliver a
prospectus in connection with any resale of those Exchange Notes.  This
Prospectus, as it may be amended or supplemented from time to time, may be used
by a broker-dealer in connection with resales of Exchange Notes received in
exchange for Notes when those Notes were acquired as a result of market making
activities or other trading activities.  The Company has agreed that, for a
period of 270 days after the consummation of the Exchange Offer, it will make
this prospectus, as amended or supplemented, available to any broker-dealer for
use in connection with any such resale.  In addition, until _____________, all
dealers effecting transactions in the Exchange Notes may be required to deliver
a prospectus./1/

     The Company will not receive any proceeds from any sale of Exchange Notes
by broker-dealers.  Exchange Notes received by any broker-dealer for its own
account pursuant to the Exchange Offer may be sold from time to time in one or
more transactions in the over-the-counter market, in negotiated transactions,
through the writing of options on the Exchange Notes or a combination of those
methods of resale, at market prices prevailing at the time of resale or at
prices related to those prevailing market prices or negotiated prices.  Any such
resale may be made directly to purchasers or to or through brokers or dealers
who may receive compensation in the form of commissions or concessions from any
such broker-dealer or the purchasers of any such Exchange Notes.  Any broker-
dealer that resells Exchange Notes that were received by it for its own account
pursuant to the Exchange Offer and any broker or dealer that participates in a
distribution of those Exchange Notes may be deemed to be an "underwriter" within
the meaning of the Securities Act and any profit on any such resale of Exchange
Notes and any commission or concessions received by any such person may be
deemed to be underwriting compensation under the Securities Act.  The Letter of
Transmittal states that, by acknowledging that it will deliver and by delivering
a prospectus, a broker-dealer will not be deemed to admit that it is an
"underwriter" within the meaning of the Securities Act.

     For a period of 270 days after the Expiration Date the Company will
promptly send additional copies of this Prospectus, and any amendment or
supplement to this Prospectus, to any broker-dealer that requests those
documents in the Letter of Transmittal. The Company has agreed to pay all
expenses incident to the Exchange Offer other than commissions or concessions of
any broker or dealer and transfer taxes, if any, and will indemnify the Holders
of the Securities (including any broker-dealer) against certain liabilities,
including liabilities under the Securities Act.

__________________
     /1/   In addition, the legend required by Item 502(b) of Regulation S-K
will appear on the back cover page of the Exchange Offer prospectus.
<PAGE>

                                                                         ANNEX D

     [_]  CHECK HERE IF YOU ARE A BROKER-DEALER AND WISH TO RECEIVE 10
          ADDITIONAL COPIES OF THE PROSPECTUS AND 10 COPIES OF ANY AMENDMENT OR
          SUPPLEMENT THERETO.

          Name:
          Address:

If the undersigned is not a broker-dealer, the undersigned represents that it is
not engaged in, and does not intend to engage in, a distribution of Exchange
Notes.  If the undersigned is a broker-dealer that will receive Exchange Notes
for its own account in exchange for Notes that were acquired as a result of
market-making activities or other trading activities, it acknowledges that it
will deliver a prospectus in connection with any resale of such Exchange Notes;
however, by so acknowledging and by delivering a prospectus, the undersigned
will not be deemed to admit that it is an "underwriter" within the meaning of
the Securities Act.

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