Document:

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                                                                     EXHIBIT 4.1

                            STOCK PURCHASE AGREEMENT

Esperion Therapeutics, Inc.
3621 S. State Street
695 KMS Place
Ann Arbor, MI  48108

Ladies & Gentlemen:

         The undersigned, _________________________________(the "Investor"),
hereby confirms its agreement with you as follows:

1.       This Stock Purchase Agreement (the "Agreement") is made as of July
__, 2001 between Esperion Therapeutics, Inc., a Delaware corporation (the
"Company"), and the Investor.

2.       The Company has authorized the sale and issuance of up to 3,500,000
shares (the "Shares") of common stock of the Company, $.001 par value per share
(the "Common Stock"), subject to adjustment by the Company, to certain investors
in a private placement (the "Offering").

3.       The Company and the Investor agree that the Investor will purchase
from the Company and the Company will issue and sell to the Investor ___________
Shares, for a purchase price of $_______ per share, or an aggregate purchase
price of $_______________, pursuant to the Terms and Conditions for Purchase of
Shares attached hereto as Annex I and incorporated herein by reference as if
fully set forth herein (the "Terms and Conditions"). Unless otherwise requested
by the Investor, certificates representing the Shares purchased by the Investor
will be registered in the Investor's name and address as set forth below.

4.       The Investor represents that, except as set forth below, (a) it has
had no position, office or other material relationship within the past three
years with the Company or persons known to it to be affiliates of the Company,
(b) neither it, nor any group of which it is a member or to which it is related,
beneficially owns (including the right to acquire or vote) any securities of the
Company and (c) it has no direct or indirect affiliation or association with any
NASD member as of the date hereof. Exceptions:

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(If no exceptions, write "none." If left blank, response will be deemed to be
"none.")

         The Investor hereby confirms, by signing in the space provided below,
that the foregoing correctly sets forth the agreement between the Investor and
the Company with respect to the purchase of Shares in the Offering. By executing
this Agreement, the Investor acknowledges that the Company may use the
information in paragraph 4 above and the name and address information below in
preparation of the Registration Statement (as defined in Annex 1).

AGREED AND ACCEPTED:
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<TABLE>
<S><C>
ESPERION THERAPEUTICS, INC.            Investor:
                                                 ---------------------------------------------------

                                       By:
                                           ---------------------------------------------------------
-------------------------------
By:                                    Print Name:
Title:                                             -------------------------------------------------

                                       Title:
                                              ------------------------------------------------------

                                       Address:
                                                ----------------------------------------------------

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

                                       Tax ID No.:
                                                   -------------------------------------------------

                                       Contact name:
                                                     -----------------------------------------------

                                       Telephone:
                                                  --------------------------------------------------

                                       Fax:
                                            --------------------------------------------------------

                                       E-mail:*
                                                ----------------------------------------------------

                                       Name in which shares should be registered (if different):

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</TABLE>

*By providing an e-mail address, the Investor hereby consents to electronic
delivery of the documents and notices required to be delivered pursuant to this
Agreement.

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<PAGE>   2

                                     ANNEX I

                   TERMS AND CONDITIONS FOR PURCHASE OF SHARES

         1.   Authorization and Sale of the Shares. Subject to these Terms and
Conditions, the Company has authorized the sale of up to 3,500,000 Shares. The
Company reserves the right to increase or decrease this number.

         2.   Agreement to Sell and Purchase the Shares; Subscription Date.

              2.1 At the Closing (as defined in Section 3), the Company will
sell to the Investor, and the Investor will purchase from the Company, upon the
terms and conditions hereinafter set forth, the number of Shares set forth in
Paragraph 3 of the Stock Purchase Agreement to which these Terms and Conditions
are attached at the purchase price set forth thereon.

              2.2 The Company may enter into the same form of Stock Purchase
Agreement, including these Terms and Conditions, with certain other investors
(the "Other Investors") and expects to complete sales of Shares to them. (The
Investor and the Other Investors are hereinafter sometimes collectively referred
to as the "Investors," and the Stock Purchase Agreement to which these Terms and
Conditions are attached and the Stock Purchase Agreements (including attached
Terms and Conditions) executed by the Other Investors are hereinafter sometimes
collectively referred to as the "Agreements.") The Company may accept executed
Agreements from Investors for the purchase of Shares commencing upon the date on
which the Company provides the Investors with the proposed purchase price per
Share and concluding upon the date (the "Subscription Date") on which the
Company has (i) executed Agreements with Investors for the purchase of at least
2,000,000 Shares, and (ii) notified Robertson Stephens, Inc., in its capacity as
placement agent for this transaction, in writing that it is no longer accepting
additional Agreements from Investors for the purchase of Shares. The Company may
not enter into any Agreements after the Subscription Date.

         3. Delivery of the Shares at Closing. The completion of the purchase
and sale of the Shares (the "Closing") shall occur on July __, 2001 (the
"Closing Date"), at the offices of the Company's counsel or at such other place
as may be agreed upon by the Company and the Placement Agent. At the Closing,
the Company shall deliver to the Investor, or a representative of the Investor,
one or more stock certificates representing the number of Shares set forth in
Paragraph 3 of the Stock Purchase Agreement, each such certificate to be
registered in the name of the Investor or, if so indicated on the signature page
of the Stock Purchase Agreement, in the name of a nominee designated by the
Investor.

         The Company's obligation to issue the Shares to the Investor shall be
subject to the following conditions, any one or more of which may be waived by
the Company: (a) prior receipt by the Company of a certified or official bank
check or wire transfer of funds in the full amount of the purchase price for the
Shares being purchased hereunder as set forth in Paragraph 3 of the Stock
Purchase Agreement; (b) completion of the purchases and sales under the
Agreements with the Other Investors; and (c) the accuracy of the representations
and warranties made by the Investors and the fulfillment of those undertakings
of the Investors to be fulfilled prior to the Closing.

         The Investor's obligation to purchase the Shares shall be subject to
the following conditions, any one or more of which may be waived by the
Investor: (a) Investors shall have executed Agreements for the purchase of at
least 2,000,000 Shares, (b) the representations and warranties of the Company
set forth herein shall be true and correct as of the Closing Date in all
material respects and (c) the Investor shall have received such documents as
such Investor shall reasonably have requested, including, a standard opinion of
counsel to the Company as to the matters set forth in Section 4.2 and as to
exemption from the registration requirements of the Securities Act of 1933, as
amended (the "Securities Act"), of the sale of the Shares.

         4. Representations, Warranties and Covenants of the Company. The
Company hereby represents and warrants to, and covenants with, the Investor, as
follows:

            4.1 Organization. The Company is duly organized and validly
existing in good standing under the laws of the jurisdiction of its
organization. Each of the Company and its Subsidiaries (as defined in Rule 405
under the Securities Act) has full power and authority to own, operate and
occupy its properties and to conduct its business as presently conducted and as
described in the documents filed by the Company under the Securities Exchange
Act of 1934, as amended (the "Exchange Act"), since the end of its most recently
completed fiscal year through the date hereof, including, without limitation,
its report on Form 10-K for the year ended December 31, 2000 and its report on
Form 10-Q for the quarter ending March 31, 2001 (the "Exchange Act Documents")
and is registered or qualified to do business and in good standing in each
jurisdiction in which the nature of the

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business conducted by it or the location of the properties owned or leased by it
requires such qualification and where the failure to be so qualified would have
a material adverse effect upon the financial condition, earnings, business or
business prospects, properties or operations of the Company and its
Subsidiaries, considered as one enterprise (a "Material Adverse Effect"), and no
proceeding has been instituted in any such jurisdiction, revoking, limiting or
curtailing, or seeking to revoke, limit or curtail, such power and authority or
qualification.

              4.2 Due Authorization and Valid Issuance. The Company has all
requisite power and authority to execute, deliver and perform its obligations
under the Agreements, and the Agreements have been duly authorized and validly
executed and delivered by the Company and constitute legal, valid and binding
agreements of the Company enforceable against the Company in accordance with
their terms, except as rights to indemnity and contribution may be limited by
state or federal securities laws or the public policy underlying such laws,
except as enforceability may be limited by applicable bankruptcy, insolvency,
reorganization, moratorium or similar laws affecting creditors' and contracting
parties' rights generally and except as enforceability may be subject to general
principles of equity (regardless of whether such enforceability is considered in
a proceeding in equity or at law). The Shares being purchased by the Investor
hereunder will, upon issuance and payment therefor pursuant to the terms hereof,
be duly authorized, validly issued, fully-paid and nonassessable.

              4.3 Non-Contravention. The execution and delivery of the
Agreements, the issuance and sale of the Shares under the Agreements, the
fulfillment of the terms of the Agreements and the consummation of the
transactions contemplated thereby will not (A) conflict with or constitute a
violation of, or default (with the passage of time or otherwise) under, (i) any
material bond, debenture, note or other evidence of indebtedness, lease,
contract, indenture, mortgage, deed of trust, loan agreement, joint venture or
other agreement or instrument to which the Company or any Subsidiary is a party
or by which it or any of its Subsidiaries or their respective properties are
bound, (ii) the charter, by-laws or other organizational documents of the
Company or any Subsidiary, or (iii) any law, administrative regulation,
ordinance or order of any court or governmental agency, arbitration panel or
authority applicable to the Company or any Subsidiary or their respective
properties, except in the case of clauses (i) and (iii) for any such conflicts,
violations or defaults which are not reasonably likely to have a Material
Adverse Effect or (B) result in the creation or imposition of any lien,
encumbrance, claim, security interest or restriction whatsoever upon any of the
material properties or assets of the Company or any Subsidiary or an
acceleration of indebtedness pursuant to any obligation, agreement or condition
contained in any material bond, debenture, note or any other evidence of
indebtedness or any material indenture, mortgage, deed of trust or any other
agreement or instrument to which the Company or any Subsidiary is a party or by
which any of them is bound or to which any of the material property or assets of
the Company or any Subsidiary is subject except in cases not reasonably likely
to have a Material Adverse Effect. No consent, approval, authorization or other
order of, or registration, qualification or filing with, any regulatory body,
administrative agency, or other governmental body in the United States or any
other person is required for the execution and delivery of the Agreements and
the valid issuance and sale of the Shares to be sold pursuant to the Agreements,
other than such as have been made or obtained, and except for any post-closing
securities filings or notifications required to be made under federal or state
securities laws.

              4.4 Capitalization. The capitalization of the Company as of March
31, 2001 is as set forth in the most recent applicable Exchange Act Documents,
increased as set forth in the next sentence. The Company has not issued any
capital stock since that date other than pursuant to (i) employee benefit plans
disclosed in the Exchange Act Documents, or (ii) outstanding warrants, options
or other securities disclosed in the Exchange Act Documents. The Shares to be
sold pursuant to the Agreements have been duly authorized, and when issued and
paid for in accordance with the terms of the Agreements will be duly and validly
issued, fully paid and nonassessable. The outstanding shares of capital stock of
the Company have been duly and validly issued and are fully paid and
nonassessable, have been issued in compliance with all federal and state
securities laws, and were not issued in violation of any preemptive rights or
similar rights to subscribe for or purchase securities. Except as set forth in
or contemplated by the Exchange Act Documents, there are no outstanding rights
(including, without limitation, preemptive rights), warrants or options to
acquire, or instruments convertible into or exchangeable for, any unissued
shares of capital stock or other equity interest in the Company or any
Subsidiary, or any contract, commitment, agreement, understanding or arrangement
of any kind to which the Company is a party or of which the Company has
knowledge and relating to the issuance or sale of any capital stock of the
Company or any Subsidiary, any such convertible or exchangeable securities or
any such rights, warrants or options. Without limiting the foregoing, except for
the registration rights contemplated in this Agreement, no preemptive right,
co-sale right, right of first refusal, registration right, or other similar
right exists with respect to the Shares or the issuance and sale thereof. No
further approval or authorization of any stockholder, the Board of Directors of
the Company or others is required for the issuance and sale of the Shares. The
Company owns the entire equity interest in each of its Subsidiaries, free and
clear of any pledge, lien, security interest, encumbrance, claim or equitable
interest, other than as described in the Exchange Act Documents. Except as
disclosed in the Exchange Act Documents, there are no stockholders agreements,
voting agreements or other similar agreements with respect to

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<PAGE>   4
the Common Stock to which the Company is a party or, to the knowledge of the
Company, between or among any of the Company's stockholders.

              4.5 Legal Proceedings. There is no material legal or governmental
proceeding pending or, to the knowledge of the Company, threatened to which the
Company or any Subsidiary is or may be a party or of which the business or
property of the Company or any Subsidiary is subject that is not disclosed in
the Exchange Act Documents.

              4.6 No Violations. Neither the Company nor any Subsidiary is in
violation of its charter, bylaws, or other organizational document, or in
violation of any law, administrative regulation, ordinance or order of any court
or governmental agency, arbitration panel or authority applicable to the Company
or any Subsidiary, which violation, individually or in the aggregate, would be
reasonably likely to have a Material Adverse Effect, or is in default (and there
exists no condition which, with the passage of time or otherwise, would
constitute a default) in any material respect in the performance of any bond,
debenture, note or any other evidence of indebtedness in any indenture,
mortgage, deed of trust or any other material agreement or instrument to which
the Company or any Subsidiary is a party or by which the Company or any
Subsidiary is bound or by which the properties of the Company or any Subsidiary
are bound, which would be reasonably likely to have a Material Adverse Effect.

              4.7 Governmental Permits, Etc. With the exception of the matters
which are dealt with separately in Sections 4.1, 4.11, 4.12, and 4.13, each of
the Company and its Subsidiaries has all necessary franchises, licenses,
certificates and other authorizations from any foreign, federal, state or local
government or governmental agency, department, or body that are currently
necessary for the operation of the business of the Company and its Subsidiaries
as currently conducted and as described in the Exchange Act Documents except
where the failure to currently possess such documents or authorizations could
not reasonably be expected to have a Material Adverse Effect.

              4.8 Intellectual Property. Except as specifically disclosed in the
Exchange Act Documents (i) each of the Company and its Subsidiaries owns or
possesses sufficient rights to use all material patents, patent rights,
trademarks, copyrights, licenses, inventions, trade secrets, trade names and
know-how (collectively, "Intellectual Property") described or referred to in the
Exchange Act Documents as owned or possessed by it or that are necessary for the
conduct of its business as now conducted or as proposed to be conducted as
described in the Exchange Act Documents except where the failure to currently
own or possess would not have a Material Adverse Effect, (ii) neither the
Company nor any of its Subsidiaries is infringing, or has received any notice
of, or has any knowledge of, any asserted infringement by the Company or any of
its Subsidiaries of, any rights of a third party with respect to any
Intellectual Property that, individually or in the aggregate, would have a
Material Adverse Effect and (iii) neither the Company nor any of its
Subsidiaries has received any notice of, or has any knowledge of, infringement
by a third party with respect to any Intellectual Property rights of the Company
or of any Subsidiary that, individually or in the aggregate, would have a
Material Adverse Effect.

              4.9 Financial Statements; Accountants. The consolidated financial
statements of the Company and the related notes contained in the Exchange Act
Documents present fairly, in accordance with generally accepted accounting
principles, the financial position of the Company and its Subsidiaries as of the
dates indicated, and the results of its operations and cash flows for the
periods therein specified and are consistent with the books and records of the
Company and its Subsidiaries except that the unaudited interim financial
statements were or are subject to normal and recurring year-end adjustments
which are not expected to be material in amount. Such financial statements
(including the related notes) have been prepared in accordance with generally
accepted accounting principles applied on a consistent basis throughout the
periods therein specified, except as may be included in the notes to such
financial statements, or in the case of unaudited statements, as may be
permitted by the SEC on Form 10-Q under the Exchange Act and except as disclosed
in the Exchange Act Documents. The other financial information contained in the
Exchange Act Documents has been prepared on a basis consistent with the
financial statements of the Company. To the Company's knowledge, Arthur
Andersen, LLP, who the Company expects will consent to the inclusion in the
Registration Statement referred to in Section 7.1 hereof of its opinion with
respect to the financial statements to be incorporated by reference from the
Company's Annual Report on Form 10-K for the year ended December 31, 2000 into
the Registration Statement (as defined below) and the prospectus which forms a
part thereof, are independent accountants as required by the Securities Act and
the rules and regulations promulgated thereunder.

              4.10 No Material Adverse Change. Except as disclosed in the
Exchange Act Documents, since March 31, 2001, there has not been (i) any
material adverse change in the financial condition or earnings of the Company
and its Subsidiaries considered as one enterprise, (ii) any material adverse
event affecting the Company or its Subsidiaries, (iii) any obligation, direct or
contingent, that is material to the Company and its Subsidiaries considered as
one enterprise, incurred by the Company, except obligations incurred in the
ordinary course of business, (iv) any dividend or distribution of any kind
declared, paid or made on the

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capital stock of the Company or any of its Subsidiaries, or (v) any loss or
damage (whether or not insured) to the physical property of the Company or any
of its Subsidiaries which has been sustained which has had a Material Adverse
Effect.

              4.11 NASDAQ Compliance. The Company's Common Stock is registered
pursuant to Section 12(g) of the Exchange Act and is listed on The Nasdaq
National Market of The Nasdaq Stock Market, Inc. (the "Nasdaq National Market"),
and the Company has taken no action designed to, or likely to have the effect
of, terminating the registration of the Common Stock under the Exchange Act or
de-listing the Common Stock from the Nasdaq National Market, nor has the Company
received any notification that the Securities and Exchange Commission (the
"SEC") or the National Association of Securities Dealers, Inc. ("NASD") is
contemplating terminating such registration or listing.

              4.12 Reporting Status. The Company has filed in a timely manner
all documents that the Company was required to file under the Exchange Act
during the period from August 9, 2000, the effective date of the Company's
initial public offering to the date of this Agreement. The following documents
complied in all material respects with the SEC's requirements as of their
respective filing dates, and the information contained therein as of the date
thereof did 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 in light of the circumstances under which they were made not
misleading:

                     (a)    the proxy statement pursuant to Section 14(a) of the
                     Exchange Act, filed April 30, 2001;

                     (b)    the annual report on Form 10-K for the year ended
                     December 31, 2000, filed on April 2, 2001;

                     (c)    the quarterly report on Form 10-Q for the quarter
                     ended March 31, 2001, filed on May 11, 2001;

                     (d)    the quarterly report on Form 10-Q for the quarter
                     ended September 30, 2000 filed on November 14, 2000;

                     (e)    the quarterly report on Form 10-Q for the quarter
                     ended June 30, 2000, filed on September 21, 2000;

                     (f)    the registration on Form 8-A under the Exchange Act,
                     filed on August 4, 2000;

                     (g)    the report on Form 8-K, filed on October 6, 2000;

                     (h)    the report on Form 8-K/A, filed on November 22,
                     2000;

                     (i)    All other documents, if any, filed by the Company
                     with the SEC since August 9, 2000 pursuant to the
                     reporting requirements of the Exchange Act.

              4.13 Listing. The Company shall comply with all requirements of
the National Association of Securities Dealers, Inc. with respect to the
issuance of the Shares and the listing thereof on the Nasdaq National Market.

              4.14 No Manipulation of Stock. The Company has not taken and will
not, in violation of applicable law, take, any action designed to or that might
reasonably be expected to cause or result in stabilization or manipulation of
the price of the Common Stock to facilitate the sale or resale of the Shares.

              4.15 Company not an "Investment Company". The Company has been
advised of the rules and requirements under the Investment Company Act of 1940,
as amended (the "Investment Company Act"). The Company is not, and immediately
after receipt of payment for the Shares will not be, an "investment company" or
an entity "controlled" by an "investment company" within the meaning of the
Investment Company Act and shall conduct its business in a manner so that it
will not become subject to the Investment Company Act.

              4.16 Foreign Corrupt Practices. Neither the Company, nor to the
knowledge of the Company, any agent or other person acting on behalf of the
Company, has (i) directly or indirectly, used any corrupt funds for unlawful
contributions, gifts, entertainment or other unlawful expenses related to
foreign or domestic political activity, (ii) made any unlawful payment to
foreign or domestic government officials or employees or to any foreign or
domestic political parties or campaigns from corporate

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<PAGE>   6
funds, (iii) failed to disclose fully any contribution made by the Company (or
made by any person acting on its behalf of which the Company is aware) which is
in violation of law, or (iv) violated in any material respect any provision of
the Foreign Corrupt Practices Act of 1977, as amended.

              4.17 Contracts. The contracts described in the Exchange Act
Documents that are material to the Company are in full force and effect on the
date hereof, and neither the Company nor, to the Company's knowledge, any other
party to such contracts is in breach of or default under any of such contracts
which would have a Material Adverse Effect.

              4.18 Taxes. The Company has filed all necessary federal, state and
foreign income and franchise tax returns and has paid or accrued all taxes shown
as due thereon, and the Company has no knowledge of a tax deficiency which has
been or might be asserted or threatened against it which would have a Material
Adverse Effect.

              4.19 Transfer Taxes. On the Closing Date, all stock transfer or
other taxes (other than income taxes) which are required to be paid in
connection with the sale and transfer of the Shares to be sold to the Investor
hereunder will be, or will have been, fully paid or provided for by the Company
and all laws imposing such taxes will be or will have been fully complied with.

              4.20 Private Offering. Assuming (i) the correctness of the
representations and warranties of the Investors set forth in Section 5 hereof,
(ii) the correctness of the information provided in the Investor Questionnaire
submitted by each of the Investors and (iii) that Placement Agent's activities
are consistent with the activities permissible under Rule 506 of Regulation D of
the Securities Act, the offer and sale of Shares hereunder is exempt from
registration under the Securities Act. The Company has not distributed and will
not distribute prior to the Closing Date any offering material in connection
with this Offering and sale of the Shares other than the documents of which this
Agreement is a part or the Exchange Act Documents. The Company has not in the
past nor will it hereafter take any action independent of the placement agent to
sell, offer for sale or solicit offers to buy any securities of the Company
which would bring the offer, issuance or sale of the Shares as contemplated by
this Agreement, within the provisions of Section 5 of the Securities Act, unless
such offer or sale was or shall be within the exemptions under Section 4 of the
Securities Act.

         5.   Representations, Warranties and Covenants of the Investor.

              5.1 The Investor represents and warrants to, and covenants with,
the Company that: (i) the Investor is an "accredited investor" as defined in
Regulation D under the Securities Act and the Investor is also knowledgeable,
sophisticated and experienced in making, and is qualified to make decisions with
respect to investments in shares presenting an investment decision like that
involved in the purchase of the Shares, including investments in securities
issued by the Company and investments in comparable companies, and has
requested, received, reviewed and considered all information it deemed relevant
in making an informed decision to purchase the Shares; (ii) the Investor is
acquiring the number of Shares set forth in Section 3 of the Stock Purchase
Agreement in the ordinary course of its business and for its own account for
investment only and with no present intention of distributing any of such Shares
or any arrangement or understanding with any other persons regarding the
distribution of such Shares; (iii) the Investor will not, directly or
indirectly, offer, sell, pledge, transfer or otherwise dispose of (or solicit
any offers to buy, purchase or otherwise acquire or take a pledge of) any of the
Shares except in compliance with the Securities Act, applicable state securities
laws and the respective rules and regulations promulgated thereunder; (iv) the
Investor has answered all questions on the Investor Questionnaire for use in
preparation of the Registration Statement and the answers thereto are true,
correct and complete as of the date hereof and will be true, correct and
complete as of the Closing Date; (v) the Investor will notify the Company
immediately of any change in any of such information until such time as the
Investor has sold all of its Shares or until the Company is no longer required
to keep the Registration Statement effective; and (vi) the Investor has, in
connection with its decision to purchase the number of Shares set forth in
Paragraph 3 of the Stock Purchase Agreement, relied only upon the Exchange Act
Documents and the representations and warranties of the Company contained
herein. The Investor understands that neither this Offering nor the acquisition
of the Shares have been registered under the Securities Act or registered or
qualified under any state securities law in reliance on specific exemptions
therefrom, which exemptions may depend upon, among other things, the bona fide
nature of the Investor's investment intent as expressed herein and the
information provided in the Investor's Investor Questionnaire. Investor has
completed or caused to be completed and delivered to the Company the Investor
Questionnaire, which questionnaire is true, correct and complete in all material
respects.

              5.2 The Investor acknowledges, represents and agrees that no
action has been or will be taken in any jurisdiction outside the United States
by the Company that would permit an offering of the Shares, or possession or
distribution of offering materials in connection with the issue of the Shares,
in any jurisdiction outside the United States where legal action by the

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<PAGE>   7
Company for that purpose is required. Each Investor outside the United States
will comply with all applicable laws and regulations in each foreign
jurisdiction in which it purchases, offers, sells or delivers Shares or has in
its possession or distributes any offering material, in all cases at its own
expense.

              5.3 The Investor hereby covenants with the Company not to make any
sale of the Shares without complying with the provisions of this Agreement and
without causing the prospectus delivery requirement under the Securities Act to
be satisfied, and the Investor acknowledges that the certificates evidencing the
Shares will be imprinted with a legend that prohibits their transfer except in
accordance therewith. The Investor acknowledges that there may occasionally be
times when the Company determines that it must suspend the use of the prospectus
forming a part of the Registration Statement, as set forth in Section 7.2(c).

              5.4 The Investor further represents and warrants to, and covenants
with, the Company that (i) the Investor has full right, power, authority and
capacity to enter into this Agreement and to consummate the transactions
contemplated hereby and has taken all necessary action to authorize the
execution, delivery and performance of this Agreement, and (ii) this Agreement
constitutes a valid and binding obligation of the Investor enforceable against
the Investor in accordance with its terms, except as enforceability may be
limited by applicable bankruptcy, insolvency, reorganization, moratorium or
similar laws affecting creditors' and contracting parties' rights generally and
except as enforceability may be subject to general principles of equity
(regardless of whether such enforceability is considered in a proceeding in
equity or at law) and except as the indemnification agreements of the Investors
herein may be legally unenforceable.

              5.5 Investor will not use any of the restricted Shares acquired
pursuant to this Agreement to cover any short position in the Common Stock of
the Company if doing so would be in violation of applicable securities laws.

              5.6 The Investor understands that nothing in the Exchange Act
Documents, this Agreement or any other materials presented to the Investor in
connection with the purchase and sale of the Shares constitutes legal, tax or
investment advice. The Investor has consulted such legal, tax and investment
advisors as it, in its sole discretion, has deemed necessary or appropriate in
connection with its purchase of Shares.

         6.   Survival of Representations, Warranties and Agreements.
Notwithstanding any investigation made by any party to this Agreement, all
covenants, agreements, representations and warranties made by the Company and
the Investor herein shall survive the execution of this Agreement, the delivery
to the Investor of the Shares being purchased and the payment therefor.

         7.   Registration of the Shares; Compliance with the Securities Act.

              7.1    Registration Procedures and Other Matters. The Company
                     shall:

                        (a) subject to receipt of necessary information from the
Investors after prompt request from the Company to the Investors to provide such
information, prepare and file with the SEC, within 10 days after the Closing
Date, (or, if the tenth day after the Closing Date is not a business day, then
the first business day thereafter) a registration statement on Form S-3 (the
"S-3 Registration Statement") to enable the resale of the Shares by the
Investors from time to time through the automated quotation system of the Nasdaq
National Market or in privately-negotiated transactions;

                        (b) use its best efforts, subject to receipt of
necessary information from the Investors after prompt request from the Company
to the Investors to provide such information, to cause the S-3 Registration
Statement to become effective within 30 days after the S-3 Registration
Statement is filed by the Company (or, if the thirtieth day is not a business
day, the first business day thereafter), such efforts to include, without
limiting the generality of the foregoing, preparing and filing with the SEC in
such 30-day period any financial statements that are required to be filed prior
to the effectiveness of such S-3 Registration Statement;

                        (c) use its best efforts to prepare and file with the
SEC such amendments and supplements to the Registration Statement and the
prospectus used in connection therewith as may be necessary to keep the
Registration Statement current, effective and free from any material
misstatement or omission to state a material fact for a period not exceeding,
with respect to each Investor's Shares purchased hereunder, the earlier of (i)
the second anniversary of the Closing Date, (ii) the date on which the Investor
may sell all Shares then held by the Investor without restriction by the volume
limitations of Rule 144(e) of the

                                      -12-
<PAGE>   8

Securities Act, or (iii) such time as all Shares purchased by such Investor in
this Offering have been sold pursuant to a registration statement;

                        (d) furnish to the Investor with respect to the Shares
registered under the Registration Statement such number of copies of the
Registration Statement, prospectuses and preliminary prospectuses in conformity
with the requirements of the Securities Act and such other documents as the
Investor may reasonably request, in order to facilitate the public sale or other
disposition of all or any of the Shares by the Investor; provided, however, that
the obligation of the Company to deliver copies of prospectuses or preliminary
prospectuses to the Investor shall be subject to the receipt by the Company of
reasonable assurances from the Investor that the Investor will comply with the
applicable provisions of the Securities Act and of such other securities or blue
sky laws as may be applicable in connection with any use of such prospectuses or
preliminary prospectuses;

                        (e) file documents required of the Company for normal
blue sky clearance in states specified in writing by the Investor and use its
best efforts to maintain such blue sky qualifications during the period the
Company is required to maintain the effectiveness of the Registration Statement
pursuant to Section 7.1(d); provided, however, that the Company shall not be
required to qualify to do business or consent to service of process in any
jurisdiction in which it is not now so qualified or has not so consented;

                        (f) bear all expenses in connection with the procedures
in paragraph (a) through (e) of this Section 7.1 and the registration of the
Shares pursuant to the Registration Statement except with respect to any legal
or attorney fees incurred by any of the Investors in connection with the
Registration Statement and any amendments thereto; and

                        (g) advise the Investor, promptly after it shall receive
notice or obtain knowledge of the issuance of any stop order by the SEC delaying
or suspending the effectiveness of the Registration Statement or of the
initiation or threat of any proceeding for that purpose; and it will promptly
use its best efforts to prevent the issuance of any stop order or to obtain its
withdrawal at the earliest possible moment if such stop order should be issued.

         The Investor acknowledges that the Company may include on the
Registration Statement; shares of common stock of the company for resale by
certain other stockholders of the Company, and that the Company may file a
subsequent registration statement for the resale of shares of common stock by
certain other stockholder of the Company. In no other event at any time before
the Registration Statement becomes effective with respect to the Shares shall
the Company publicly announce or file any other registration statement, other
than registrations on Form S-8, without the prior written consent of a majority
in interest of the Investors.

         The Company understands that the Investor disclaims being an
underwriter, but the Investor being deemed an underwriter by the SEC shall not
relieve the Company of any obligations it has hereunder; provided, however that
if the Company receives notification from the SEC that the Investor is deemed an
underwriter, then the period by which the Company is obligated to exercise its
best efforts to submit an acceleration request to the SEC shall be extended to
the earlier of (i) the 90th day after such SEC notification, or (ii) 120 days
after the initial filing of the Registration Statement with the SEC.

                                      -13-

<PAGE>   9

                 7.2    Transfer of Shares After Registration; Suspension.

                        (a) The Investor agrees that it will not effect any
disposition of the Shares or its right to purchase the Shares that would
constitute a sale within the meaning of the Securities Act except as
contemplated in the Registration Statement referred to in Section 7.1 and as
described below or as otherwise permitted by law, and that it will promptly
notify the Company of any changes in the information set forth in the
Registration Statement regarding the Investor or its plan of distribution.

                        (b) Except in the event that paragraph (c) below
applies, the Company shall (i) if deemed necessary by the Company, prepare and
file from time to time with the SEC a post-effective amendment to the
Registration Statement or a supplement to the related prospectus or a supplement
or amendment to any document incorporated therein by reference or file any other
required document so that such Registration Statement will 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
so that, as thereafter delivered to purchasers of the Shares being sold
thereunder, such prospectus will 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, in light of the circumstances under which they
were made, not misleading; (ii) provide the Investor copies of any documents
filed pursuant to Section 7.2(b)(i); and (iii) inform each Investor that the
Company has complied with its obligations in Section 7.2(b)(i) (or that, if the
Company has filed a post-effective amendment to the Registration Statement which
has not yet been declared effective, the Company will notify the Investor to
that effect, will use its best efforts to secure the effectiveness of such
post-effective amendment as promptly as possible and will promptly notify the
Investor when the amendment has become effective).

                        (c) Subject to paragraph (d) below, in the event (i) of
any request by the SEC or any other federal or state governmental authority
during the period of effectiveness of the Registration Statement for amendments
or supplements to a Registration Statement or related prospectus or for
additional information; (ii) of the issuance by the SEC or any other federal or
state governmental authority of any stop order suspending the effectiveness of a
Registration Statement or the initiation of any proceedings for that purpose;
(iii) of the receipt by the Company of any notification with respect to the
suspension of the qualification or exemption from qualification of any of the
Shares for sale in any jurisdiction or the initiation or threatening of any
proceeding for such purpose; or (iv) of any event or circumstance which, upon
the advice of its counsel, necessitates the making of any changes in the
Registration Statement or prospectus, or any document incorporated or deemed to
be incorporated therein by reference, so that, in the case of the Registration
Statement, it will not contain any untrue statement of a material fact or any
omission to state a material fact required to be stated therein or necessary to
make the statements therein not misleading, and that in the case of the
prospectus, it will not contain any untrue statement of a material fact or any
omission to state a 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; then the Company shall deliver a certificate in writing to
the Investor (the "Suspension Notice") to the effect of the foregoing and, upon
receipt of such Suspension Notice, the Investor will refrain from selling any
Shares pursuant to the Registration Statement (a "Suspension") until the
Investor's receipt of copies of a supplemented or amended prospectus prepared
and filed by the Company, or until it is advised in writing by the Company that
the current prospectus may be used, and has received copies of any additional or
supplemental filings that are incorporated or deemed incorporated by reference
in any such prospectus. In the event of any Suspension, the Company will use its
best efforts to cause the use of the prospectus so suspended to be resumed as
soon as reasonably practicable within 20 business days after the delivery of a
Suspension Notice to the Investor. In addition to and without limiting any other
remedies (including, without limitation, at law or at equity) available to the
Investor, the Investor shall be entitled to specific performance in the event
that the Company fails to comply with the provisions of this Section 7.2(c).

                        (d) Notwithstanding the foregoing paragraphs of this
Section 7.2, the Investor shall not be prohibited from selling Shares under the
Registration Statement as a result of Suspensions on more than two occasions of
not more than 30 days each in any twelve-month period, unless, in the good faith
judgment of the Company's Board of Directors, upon the written opinion of
counsel, the sale of Shares under the Registration Statement in reliance on this
paragraph 7.2(d) would be reasonably likely to cause a violation of the
Securities Act or the Exchange Act and result in liability to the Company.

                        (e) Provided that a Suspension is not then in effect,
the Investor may sell Shares under the Registration Statement, provided that it
arranges for delivery of a current prospectus to the transferee of such Shares.
Upon receipt of a request therefor, the Company has agreed to provide an
adequate number of current prospectuses to the Investor and to supply copies to
any other parties requiring such prospectuses.

                                      -14-

<PAGE>   10
                        (f) In the event of a sale of Shares by the Investor
pursuant to the Registration Statement, the Investor must also deliver to the
Company's transfer agent, with a copy to the Company, a Certificate of
Subsequent Sale substantially in the form attached hereto as Exhibit A, and its
stock certificate, so that the Shares may be properly transferred.

                 7.3    Indemnification. For the purpose of this Section 7.3:

                 (i) the term "Selling Stockholder" shall include the Investor
and any affiliate of such Investor;

                 (ii) the term "Registration Statement" shall include the
prospectus in the form first filed with the SEC pursuant to Rule 424(b) of the
Securities Act or filed as part of the Registration Statement at the time of
effectiveness if no Rule 424(b) filing is required, and any exhibit, supplement
or amendment included in or relating to the Registration Statement referred to
in Section 7.1; and

                 (iii) the term "untrue statement" shall include any untrue
statement or alleged untrue statement, or any omission or alleged omission to
state in the Registration Statement a material fact required to be stated
therein or necessary to make the statements therein, in the light of the
circumstances under which they were made, not misleading.

                        (a) The Company agrees to indemnify and hold harmless
each Selling Stockholder from and against any losses, claims, damages or
liabilities to which such Selling Stockholder may become subject (under the
Securities Act or otherwise) insofar as such losses, claims, damages or
liabilities (or actions or proceedings in respect thereof) arise out of, or are
based upon (i) any breach of the representations or warranties of the Company
contained herein or failure to comply with the covenants and agreements of the
Company contained herein, (ii) any untrue statement of a material fact contained
in the Registration Statement as amended at the time of effectiveness or any
omission of a material fact required to be stated therein or necessary to make
the statements therein not misleading, or (iii) any failure by the Company to
fulfill any undertaking included in the Registration Statement at the time of
effectiveness, and the Company will reimburse such Selling Stockholder for any
reasonable and documented legal expenses and any other actual, accountable
out-of -pocket expenses reasonably incurred in investigating, defending or
preparing to defend any such action, proceeding or claim, or preparing to defend
any such action, proceeding or claim, provided, however, that the Company shall
not be liable in any such case to the extent that such loss, claim, damage or
liability arises out of, or is based upon, an untrue statement made in such
Registration Statement or any omission of a material fact required to be stated
therein or necessary to make the statements therein not misleading in reliance
upon and in conformity with written information furnished to the Company by or
on behalf of such Selling Stockholder specifically for use in preparation of the
Registration Statement or the failure of such Selling Stockholder to comply with
its covenants and agreements contained in Section 7.2 hereof respecting the sale
of the Shares or any statement or omission in any prospectus that is corrected
in any subsequent prospectus that was delivered to the Selling Stockholder prior
to the pertinent sale or sales by the Selling Stockholder. The Company shall
reimburse each Selling Stockholder for the amounts provided for herein within a
reasonable period of time after demand thereof.

                        (b) The Investor agrees to indemnify and hold harmless
the Company (and each person, if any, who controls the Company within the
meaning of Section 15 of the Securities Act, each officer of the Company who
signs the Registration Statement and each director of the Company) from and
against any losses, claims, damages or liabilities to which the Company (or any
such officer, director or controlling person) may become subject (under the
Securities Act or otherwise), insofar as such losses, claims, damages or
liabilities (or actions or proceedings in respect thereof) arise out of, or are
based upon, (i) any failure to comply with the covenants and agreements
contained in Section 7.2 hereof respecting sale of the Shares, or (ii) any
untrue statement of a material fact contained in the Registration Statement or
any omission of a material fact required to be stated therein or necessary to
make the statements therein not misleading if such untrue statement or omission
was made in reliance upon and in conformity with written information furnished
by or on behalf of the Investor specifically for use in preparation of the
Registration Statement, and the Investor will reimburse the Company (or such
officer, director or controlling person), as the case may be, for any legal or
other expenses reasonably incurred in investigating, defending or preparing to
defend any such action, proceeding or claim.

                        (c) Promptly after receipt by any indemnified person of
a notice of a claim or the beginning of any action in respect of which indemnity
is to be sought against an indemnifying person pursuant to this Section 7.3,
such indemnified person shall notify the indemnifying person in writing of such
claim or of the commencement of such action, but the omission to so notify the
indemnifying person will not relieve it from any liability which it may have to
any indemnified person under this Section 7.3 (except to the extent that such
omission materially and adversely affects the indemnifying person's ability to
defend such action) or from any liability otherwise than under this Section 7.3.
Subject to the provisions hereinafter stated, in case any

                                      -15-
<PAGE>   11
such action shall be brought against an indemnified person, the indemnifying
person shall be entitled to participate therein, and, to the extent that it
shall elect by written notice delivered to the indemnified person promptly after
receiving the aforesaid notice from such indemnified person, shall be entitled
to assume the defense thereof, with counsel reasonably satisfactory to such
indemnified person. After notice from the indemnifying person to such
indemnified person of its election to assume the defense thereof, such
indemnifying person shall not be liable to such indemnified person for any legal
expenses subsequently incurred by such indemnified person in connection with the
defense thereof, provided, however, that if there exists or shall exist a
conflict of interest that would make it inappropriate, in the opinion of counsel
to the indemnified person, for the same counsel to represent both the
indemnified person and such indemnifying person or any affiliate or associate
thereof, the indemnified person shall be entitled to retain its own counsel at
the expense of such indemnifying person; provided, however, that no indemnifying
person shall be responsible for the fees and expenses of more than one separate
counsel (together with appropriate local counsel) for all indemnified parties.
In no event shall any indemnifying person be liable in respect of any amounts
paid in settlement of any action unless the indemnifying person shall have
approved the terms of such settlement; provided that such consent shall not be
unreasonably withheld. No indemnifying person shall, without the prior written
consent of the indemnified person, effect any settlement of any pending or
threatened proceeding in respect of which any indemnified person is or could
have been a party and indemnification could have been sought hereunder by such
indemnified person, unless such settlement includes an unconditional release of
such indemnified person from all liability on claims that are the subject matter
of such proceeding.

                        (d) If the indemnification provided for in this Section
7.3 is unavailable to or insufficient to hold harmless an indemnified person
under subsection (a) or (b) above in respect of any losses, claims, damages or
liabilities (or actions or proceedings in respect thereof) referred to therein,
then each indemnifying person shall contribute to the amount paid or payable by
such indemnified person as a result of such losses, claims, damages or
liabilities (or actions in respect thereof) in such proportion as is appropriate
to reflect the relative fault of the Company on the one hand and the Investor,
as well as any other Selling Shareholders under such registration statement on
the other in connection with the statements or omissions or other matters which
resulted in such losses, claims, damages or liabilities (or actions in respect
thereof), as well as any other relevant equitable considerations. The relative
fault shall be determined by reference to, among other things, in the case of an
untrue statement, whether the untrue statement relates to information supplied
by the Company on the one hand or an Investor or other Selling Shareholder on
the other and the parties' relative intent, knowledge, access to information and
opportunity to correct or prevent such untrue statement. The Company and the
Investor agree that it would not be just and equitable if contribution pursuant
to this subsection (d) were determined by pro rata allocation (even if the
Investor and other Selling Shareholders were treated as one entity for such
purpose) or by any other method of allocation which does not take into account
the equitable considerations referred to above in this subsection (d). The
amount paid or payable by an indemnified person as a result of the losses,
claims, damages or liabilities (or actions in respect thereof) referred to above
in this subsection (d) shall be deemed to include any legal or other expenses
reasonably incurred by such indemnified person in connection with investigating
or defending any such action or claim. Notwithstanding the provisions of this
subsection (d), the Investor shall not be required to contribute any amount in
excess of the amount by which the net amount received by the Investor from the
sale of the Shares to which such loss relates exceeds the amount of any damages
which such Investor has otherwise been required to pay by reason of such untrue
statement. No person guilty of fraudulent misrepresentation (within the meaning
of Section 11(f) of the Securities Act) shall be entitled to contribution from
any person who was not guilty of such fraudulent misrepresentation. The
Investor's obligations in this subsection to contribute shall be in proportion
to its Investor sale of Shares to which such loss relates and shall not be joint
with any other Selling Shareholders.

                        (e) The Investor hereby acknowledges that it is a
sophisticated business person who was represented by counsel during the
negotiations regarding the provisions hereof including, without limitation, the
provisions of this Section 7.3, and is fully informed regarding said provisions.
The Investor further acknowledges that the provisions of this Section 7.3 fairly
allocate the risks involved in the Offering. The Investor and the Company are
advised that federal or state public policy as interpreted by the courts in
certain jurisdictions may be contrary to certain of the provisions of this
Section 7.3, and the Investor and the Company hereto hereby expressly waive and
relinquish any right or ability to assert such public policy as a defense to a
claim under this Section 7.3 and further agree not to attempt to assert any such
defense.

              7.4 Termination of Conditions and Obligations. The conditions
precedent imposed by Section 5 or this Section 7 upon the transferability of the
Shares shall cease and terminate as to any particular number of the Shares when
such Shares shall have been effectively registered under the Securities Act and
sold or otherwise disposed of in accordance with the intended method of
disposition set forth in the Registration Statement covering such Shares or at
such time as an opinion of counsel reasonably satisfactory to the Company shall
have been rendered to the effect that such conditions are not necessary in order
to comply with the Securities Act.

                                      -16-
<PAGE>   12

              7.5 Information Available. So long as the Registration Statement
is effective covering the resale of Shares owned by the Investor, the Company
will furnish to the Investor:

                 (a) as soon as practicable after it is available, one copy of
(i) its Annual Report to Stockholders (which Annual Report shall contain
financial statements audited in accordance with generally accepted accounting
principles by a national firm of certified public accountants), (ii) its Annual
Report on Form 10-K and (iii) its Quarterly Reports on Form 10-Q (the foregoing,
in each case, excluding exhibits);

                 (b) upon the request of the Investor, all exhibits excluded by
the parenthetical to subparagraph (a) of this Section 7.5 as filed with the SEC
and all other information that is made available to shareholders; and

                 (c) upon the reasonable request of the Investor, an adequate
number of copies of the prospectuses to supply to any other party requiring such
prospectuses; and upon the reasonable request of the Investor, the President or
the Chief Financial Officer of the Company (or an appropriate designee
identified by the Company) will meet with the Investor or a representative
thereof at the Company's headquarters to discuss all information relevant for
disclosure in the Registration Statement covering the Shares and will otherwise
cooperate with any Investor conducting an investigation for the purpose of
reducing or eliminating such Investor's exposure to liability under the
Securities Act, including the reasonable production of information at the
Company's headquarters; provided, that the Company shall not be required to
disclose any confidential information to or meet at its headquarters with any
Investor until and unless the Investor shall have entered into a confidentiality
agreement in form and substance reasonably satisfactory to the Company with the
Company with respect thereto.

                 (d) if agreed to by the Investor on the signature page to this
Agreement, the documents required to be delivered by the Company pursuant to
this Agreement, except for the prospectus or preliminary prospectus required to
be delivered pursuant to Section 7.1(d) herein, shall be delivered to the
Investor in electronic form to the e-mail address provided by the Investor on
the signature page of the Stock Purchase Agreement.

         8. Notices. All notices, requests, consents and other communications
hereunder shall be in writing, shall be mailed (A) if within the United States
by first-class registered or certified airmail, or nationally recognized
overnight express courier, postage prepaid, by facsimile or e-mail (if agreed to
by the Investor), or (B) if delivered from outside the United States, by
international express courier, facsimile or e-mail (if agreed to by the
Investor), and shall be deemed given (i) if delivered by first-class registered
or certified mail, three business days after so mailed, (ii) if delivered by
nationally recognized overnight carrier, one business day after so mailed, (iii)
if delivered by International Federal Express, two business days after so
mailed, (iv) if delivered by facsimile or e-mail, upon electronic confirmation
of receipt and shall be delivered as addressed as follows:

            (a)       if to the Company, to:

                              Esperion Therapeutics, Inc.
                              3621 S. State Street
                              695 KMS Place
                              Ann Arbor, MI  48108
                              Attn:  President

            (b)       with a copy to:

                              Morgan, Lewis & Bockius, LLP
                              1800 M Street N.W.
                              Washington D.C. 20036
                              Attention: Linda Griggs

            (c)      if to the Investor, at its mail or e-mail address on
                     the signature page hereto, or at such other address
                     or addresses as may have been furnished to the
                     Company in writing.

         9. Changes. This Agreement may not be modified or amended except
pursuant to an instrument in writing signed by the Company and the Investor.

                                      -17-

<PAGE>   13

         10. Headings. The headings of the various sections of this Agreement
have been inserted for convenience of reference only and shall not be deemed to
be part of this Agreement and do not affect its interpretation.

         11. Severability. In case any provision contained in this Agreement
should be invalid, illegal or unenforceable in any respect, the validity,
legality and enforceability of the remaining provisions contained herein shall
not in any way be affected or impaired thereby.

         12. Governing Law. This Agreement shall be governed by, and construed
in accordance with, the internal laws of the State of Delaware, without giving
effect to the principles of conflicts of law.

         13. Counterparts. This Agreement may be executed in two or more
counterparts, each of which shall constitute an original, but all of which, when
taken together, shall constitute but one instrument, and shall become effective
when one or more counterparts have been signed by each party hereto and
delivered to the other parties.

         14. Rule 144. The Company covenants that it will timely file the
reports required to be filed by it under the Securities Act and the Exchange Act
and the rules and regulations adopted by the SEC thereunder (or, if the Company
is not required to file such reports, it will, upon the request of any Investor
holding Shares purchased hereunder made after the first anniversary of the
Closing Date, make publicly available such information as necessary to permit
sales pursuant to Rule 144 under the Securities Act), and it will take such
further action as any such Investor may reasonably request, all to the extent
required from time to time to enable such Investor to sell Shares purchased
hereunder without registration under the Securities Act within the limitation of
the exemptions provided by (a) Rule 144 under the Securities Act, as such Rule
may be amended from time to time, or (b) any similar rule or regulation
hereafter adopted by the SEC. Upon the request of the Investor, the Company will
deliver to such holder a written statement as to whether it has complied with
such information and requirements.

         15. Confidential Information. The Investor represents to the Company
that, at all times during the Company's offering of the Shares, the Investor has
maintained in confidence all non-public information regarding the Company
received by the Investor from the Company or its agents, including information
about the Offering of the Shares and covenants that it will continue to maintain
in confidence such information until such information (a) becomes generally
publicly available other than through a violation of this provision by the
Investor or its agents or (b) is required to be disclosed in legal proceedings
(such as by deposition, interrogatory, request for documents, subpoena, civil
investigation demand, filing with any governmental authority or similar
process), provided, however, that before making any use or disclosure in
reliance on this subparagraph (b) the Investor shall give the Company at least
fifteen (15) days prior written notice (or such shorter period as required by
law) specifying the circumstances giving rise thereto and will furnish only that
portion of the non-public information which is legally required and will
exercise its best efforts to obtain reliable assurance that confidential
treatment will be accorded any non-public information so furnished.

                                      -18-<PAGE>   1

                                                                  EXHIBIT 4.4(a)

                      BONNEVILLE PACIFIC SECURITY AGREEMENT

                          DATED AS OF FEBRUARY 22, 2001

                                     MADE BY

                         BONNEVILLE PACIFIC CORPORATION

                                   AS GRANTOR,

                                       TO

                              THE BANK OF NEW YORK,

                                   AS TRUSTEE

<PAGE>   2

                      BONNEVILLE PACIFIC SECURITY AGREEMENT

         This SECURITY AGREEMENT dated as of February 22, 2001, made by
BONNEVILLE PACIFIC CORPORATION, a Delaware corporation (the "GRANTOR"), to THE
BANK OF NEW YORK, a New York banking corporation, in its capacity as trustee
(the "TRUSTEE") for the holders from time to time (the "HOLDERS") of the Notes
(as defined in the Indenture referred to below), issued by East Coast Power
L.L.C., a Delaware limited liability company (the "COMPANY") under the Indenture
referred to below.

                             PRELIMINARY STATEMENTS

         (1) The Company and the Trustee have entered into an indenture dated as
of April 20, 1999 (as amended, restated, supplemented or otherwise modified from
time to time, the "INDENTURE"), pursuant to which the Company issued Notes in an
aggregate principal amount of $850,000,000. Unless otherwise defined in this
Agreement, capitalized terms used in this Agreement have the meanings specified
in the Indenture.

         (2) On even date herewith, Grantor was admitted as a member of the
Company and as a condition precedent to such admission by Grantor, Trustee has
required that Grantor's membership interest in the Company be pledged to Trustee
as security under the Indenture.

         (3) Grantor has agreed to grant the security interest and make the
pledge and assignment contemplated by this Agreement.

         NOW, THEREFORE, in consideration of the premises, the Grantor hereby
agrees with the Trustee, for the benefit of the Trustee and for the ratable
benefit of the Holders of the Notes, as follows:

         SECTION 1. CERTAIN DEFINED TERMS. Unless otherwise defined in this
Section 1, (a) capitalized terms used in this Agreement have the meanings
specified in the Indenture, and (b) terms used in Article 8 or 9 of the Uniform
Commercial Code from time to time in effect in the State of New York (the
"NYUCC") are used herein as therein defined. As used in this Agreement, the
following terms shall have the following meanings (such meanings to be equally
applicable to both the singular and the plural forms of the terms defined):

         "COLLATERAL" has the meaning specified in Section 2.

         "NYUCC" has the meaning specified above in this Section 1.

         "PLEDGED INTERESTS" has the meaning specified in Section 2(a).

         "SECURED OBLIGATIONS" has the meaning specified in Section 3.

         "SECURITY COLLATERAL" has the meaning specified in Section 2(a).

                                       2
<PAGE>   3

         SECTION 2. GRANT OF SECURITY. The Grantor hereby pledges and assigns to
the Trustee, for its benefit and the ratable benefit of the Holders of the
Notes, and hereby grants to the Trustee, for its benefit and for the ratable
benefit of the Holders of the Notes, a continuing security interest in and to
all of the Grantor's right, title and interest in and to, the following (whether
consisting of investment securities, book-entry securities or other securities,
security entitlements, financial assets or other investment property, accounts,
general intangibles, instruments or documents, securities accounts, deposit
accounts or other bank, trust or cash collateral accounts, or other property,
assets or rights), whether now owned or hereafter acquired, wherever located and
whether now or hereafter existing (collectively, the "COLLATERAL"):

                  (a) all of the membership interests in the Company described
         on Schedule I hereto whether or not evidenced by certificates
         (collectively, the "PLEDGED INTERESTS"), and the certificates, if any,
         representing such interests, any security therefor and all dividends,
         distributions, profits, bonuses, premiums, income, cash, instruments
         and other property and assets from time to time received, receivable or
         otherwise distributed in respect of or in exchange for any or all of
         such membership interests (all such Collateral being, the "SECURITY
         COLLATERAL"); and

                  (b) all proceeds (including cash proceeds) of any and all of
         the foregoing Collateral (including, without limitation, proceeds that
         constitute property of the types described in clause (a) of this
         Section 2) and, to the extent not otherwise included, all (i) payments
         under insurance (whether or not the Trustee is the loss payee thereof),
         or any indemnity, warranty or guaranty, payable by reason of loss or
         damage to or otherwise with respect to any of the foregoing Collateral
         and (ii) payments and distributions made with respect to the foregoing
         Collateral.

         SECTION 3. SECURITY FOR OBLIGATIONS. This Agreement secures the payment
of all obligations, now or hereafter existing, of the Company under the
Indenture and the Notes and of the Grantor under this Agreement (including,
without limitation, any extensions, modifications, substitutions, amendments and
renewals thereof), in each case whether direct or indirect, absolute or
contingent, and whether for principal, interest, fees, indemnification payments,
contract causes of action, costs, expenses or otherwise (all such obligations
being the "SECURED OBLIGATIONS"). Without limiting the generality of the
foregoing, this Agreement secures, to the fullest extent permitted by applicable
law, the payment of all amounts that constitute part of the Secured Obligations
and would be owed by the Company to the Trustee or the Holders under the
Indenture, the Notes or the Security Documents but for the fact that they are
unenforceable or not allowable due to the existence of a bankruptcy,
reorganization or similar proceeding involving the Company.

         SECTION 4. DELIVERY OF COLLATERAL.

                  (a) The Grantor shall ensure that all certificates or
         instruments representing or evidencing Security Collateral, if any, are
         delivered to and be held by or on behalf of the Trustee pursuant hereto
         and are in suitable form for transfer by delivery or shall be
         accompanied by duly executed instruments of transfer or assignment in
         blank, all in form and substance reasonably satisfactory to the
         Trustee. The Trustee shall have the right, at

                                       3
<PAGE>   4

         any time and without notice to the Grantor, to transfer to or register
         in the name of the Trustee or any of its nominees any or all of the
         Security Collateral, subject only to the revocable rights specified in
         Section 11(b). In addition, the Trustee shall have the right at any
         time and from time to time to exchange certificates or instruments
         representing or evidencing Security Collateral held by them for
         certificates or instruments of smaller or larger denominations.

                  (b) Concurrently with the execution and delivery of this
         Agreement, the Grantor shall cause to be filed proper financing
         statements in all jurisdictions necessary or prudent to perfect and
         protect the liens and security interests created hereunder, covering
         the Collateral described herein.

         SECTION 5. REPRESENTATIONS AND WARRANTIES. The Grantor represents and
warrants as of the date of this Agreement as follows:

                  (a) The Grantor is a corporation duly organized, validly
         existing and in good standing under the laws of the State of Delaware.
         The Grantor has all corporate power and authority and all governmental
         licenses, authorizations, consents and approvals required in each case
         to carry on its business as now conducted, except to the extent that
         the failure to have such power, authority, licenses, authorizations,
         consents and approvals could not reasonably be expected to have a
         material adverse effect on the Grantor's ability to perform any of its
         obligations hereunder or a material adverse effect on the business,
         operations, assets or financial condition of the Grantor and its
         Subsidiaries taken as a whole (a "GRANTOR MATERIAL ADVERSE EFFECT").

                  (b) The execution, delivery and performance by the Grantor of
         this Agreement are within the Grantor's corporate powers, have been
         duly authorized by all necessary action of the Grantor, require, in
         respect of the Grantor, no action by or in respect of, or filing with,
         any governmental body, agency or official (other than the filing of
         financing statements in favor of the Trustee on or prior to the date
         hereof as may be required for the perfection of the Security Interest
         herein granted in the Collateral) and do not contravene, or constitute
         a default under, any provision of law or regulation (including
         Regulation X of the Board of Governors of the Federal Reserve System)
         applicable to the Grantor or Regulation U of the Board of Governors of
         the Federal Reserve System or the certificate of incorporation or
         bylaws of the Grantor or any judgment, injunction, order, decree or
         material agreement binding upon the Grantor or result in or require the
         creation or imposition of any Lien on any of the Collateral.

                  (c) This Agreement has been duly executed and delivered by the
         Grantor. This Agreement is the legal, valid and binding obligation of
         the Grantor, enforceable against the Grantor in accordance with its
         terms, except as the enforceability thereof may be limited by any
         applicable bankruptcy, insolvency, reorganization, moratorium or
         similar laws affecting creditors' rights generally and by general
         principles of equity.

                  (d) There is no pending, or to the Grantor's knowledge,
         threatened action, suit or proceeding against the Grantor before any
         court or arbitrator or any governmental

                                       4
<PAGE>   5

         body, agency or official in which there is a reasonable possibility of
         an adverse decision which could reasonably be expected to have a
         Grantor Material Adverse Effect or which in any manner draws into
         question the legality, validity, binding effect or enforceability of
         this Agreement.

                  (e) The chief place of business and chief executive office of
         the Grantor are located at the address specified in Section 17. The
         Grantor has no trade names.

                  (f) The Grantor is the legal and beneficial owner of the
         Collateral which is in existence on the date hereof free and clear of
         any Lien (other than Liens not prohibited by the Indenture), except for
         the security interest created by this Agreement. No effective financing
         statement or other instrument similar in effect covering all or any
         part of the Collateral is on file in any recording office, and the
         Grantor has not entered into any security control agreement or other
         agreement similar in effect, in each case covering all or any part of
         the Collateral, except such as may have been filed in favor of the
         Trustee relating to this Agreement or the other Security Documents.

                  (g) There are no existing options, warrants, calls or
         commitments of any character whatsoever relating to any Equity
         Interests in the Company owned by the Grantor except for this Agreement
         and the limited liability company agreement of the Company. There are
         no shareholder agreements, voting trust agreements or other agreements
         or understandings to which the Grantor is a party or by which the
         Grantor may otherwise be bound that affect the voting or other rights
         of a holder of any Equity Interest in the Company (including, without
         limitation, the ability to transfer any such Equity Interest), except
         for this Agreement and the limited liability company agreement of the
         Company.

                  (h) This Agreement, the pledge of the Collateral pursuant
         hereto and the pledge, assignment and delivery to the Trustee of the
         certificates representing the Security Collateral pursuant hereto,
         together with stock or other transfer powers duly executed in blank,
         create a valid and perfected first priority security interest in the
         Collateral, securing the payment of the Secured Obligations, and all
         filings and other actions necessary to perfect and protect such
         security interest have been duly taken.

                  (i) No consent of any other Person and no authorization,
         approval or other action by, and no notice to or filing with, any
         governmental authority or regulatory body or other third party is
         required either (i) for the grant by the Grantor of the assignment and
         security interest granted hereby, for the pledge by the Grantor of any
         of the Collateral pursuant hereto or for the execution, delivery or
         performance of this Agreement by the Grantor, (ii) for the perfection
         or continuation of perfection of the pledge, assignment and security
         interest created hereby (including the priority of such pledge,
         assignment or security interest), except for the filing of financing
         and continuation statements under the Uniform Commercial Code, which
         financing statements have been duly filed, (iii) for the exercise by
         the Trustee of its voting or other rights provided for in this
         Agreement or the remedies in respect of the Collateral pursuant to this
         Agreement, except as may be required in connection with the disposition
         of any portion of the Security Collateral by

                                       5
<PAGE>   6

         laws affecting the offering and sale of securities generally or (iv)
         consents, authorizations, approvals or other actions or filings that
         have been made or obtained on or prior to the date hereof.

         SECTION 6. FURTHER ASSURANCES; PLACE OF PERFECTION.

                  (a) The Grantor agrees that from time to time, at its sole
         expense, the Grantor will promptly execute and deliver all further
         instruments and documents, and take all further action, that may be
         necessary or prudent, or that the Trustee may reasonably request, in
         order to perfect and protect any pledge, assignment or security
         interest granted or purported to be granted hereunder (including,
         without limitation, the priority thereof) or to enable the Trustee to
         exercise and enforce its rights and remedies hereunder. Without
         limiting the generality of the foregoing, the Grantor will:

                           (i) if any Collateral shall be evidenced by a
                  certificate, promissory note or other instrument or by chattel
                  paper, deliver and pledge to the Trustee hereunder such
                  certificate, note or other instrument or such chattel paper
                  duly endorsed and accompanied by duly executed instruments of
                  transfer or assignment, all in form and substance reasonably
                  satisfactory to the Trustee; and

                           (ii) execute and file such financing statements,
                  continuation statements or other similar documents, or
                  amendments thereto, and such other instruments or notices, as
                  may be necessary or as the Trustee may deem reasonably prudent
                  and may request, in order to perfect and preserve the pledge,
                  assignment and security interest granted or purported to be
                  granted under this Agreement.

                  (b) The Grantor hereby authorizes the Trustee to cause the
         filing of one or more financing statements, continuation statements or
         other similar documents, and amendments thereto, relating to all or any
         part of the Collateral without the signature of the Grantor where
         permitted by applicable law. A photocopy or other reproduction of this
         Agreement or any financing statement or other similar document covering
         the Collateral or any part thereof shall be sufficient as a financing
         statement or other similar document where permitted by applicable law.

                  (c) The Grantor shall furnish to the Trustee from time to time
         statements and schedules further identifying and describing the
         Collateral and such other reports in connection with the Collateral as
         the Trustee may reasonably request, all in reasonable detail.

         SECTION 7. COVENANT TO GIVE FURTHER SECURITY. The Grantor hereby agrees
that, if, and at such time as, it acquires title to, or any other ownership
interest in, any additional Equity Interests in any issuer of the Pledged
Interests, it will, at its sole expense:

                  (a) as promptly as practicable and in any event within five
         (5) days after such acquisition, notify the Trustee of its acquisition
         of title thereto or such other ownership interest therein; and

                                       6
<PAGE>   7

                  (b) as promptly as practicable and in any event within 30 days
         after such acquisition, (i) duly execute and deliver such mortgages,
         pledges, assignments and/or other security agreements as are necessary
         to create a valid lien thereon and security interest therein in favor
         of the Trustee, for its benefit and the benefit of the Holders of the
         Notes, in each case in form and substance satisfactory to the Trustee,
         and (ii) make all filings and take all other actions that are necessary
         or that the Trustee may deem reasonably prudent and may request to
         perfect and protect a valid and perfected first priority lien thereon
         and security interest therein in favor of the Trustee, for its benefit
         and the benefit of the Holders of the Notes.

         SECTION 8. TRUSTEE APPOINTED ATTORNEY-IN-FACT. In addition to all of
the powers granted to the Trustee pursuant to the Indenture, the Grantor hereby
irrevocably appoints the Trustee its attorney-in-fact (which appointment is
coupled with an interest and is irrevocable), with full authority in the place
and stead of the Grantor and in the name of the Grantor or otherwise and with
full power of substitution, from time to time upon the occurrence and during the
continuation of an Event of Default, to take any action and to execute any
instrument to accomplish the purposes of this Agreement (it being understood
that the Trustee will not be required to act unless otherwise set forth herein
or in the Indenture), including, without limitation:

                  (a) upon the occurrence and during the continuation of an
         Event of Default, to ask for, demand, collect, sue for, recover,
         compromise, receive, and give acquittance and receipts for, moneys due
         and to become due under or in respect of any of the Collateral;

                  (b) to receive, endorse and collect any drafts, instruments or
         other documents or any chattel paper in connection with this Agreement
         (including, without limitation, all instruments representing or
         evidencing any interest payment or other distribution in respect of the
         Security Collateral or any part thereof) and to give full discharge for
         the same;

                  (c) to sell, transfer, assign or otherwise deal with the
         Collateral or any part thereof under, and in accordance with, the terms
         of the Indenture or Section 14 in the same manner and to the same
         extent as if the Trustee was the absolute owner thereof; and

                  (d) upon the occurrence and during the continuation of any
         Event of Default, to file any claims or take any action or institute
         any proceedings that may be necessary or that the Trustee may deem
         desirable for the collection of any of the Collateral or otherwise to
         enforce the rights of the Trustee with respect to any of the
         Collateral.

         SECTION 9. TRUSTEE MAY PERFORM. If the Grantor fails to make any
payment required to be made by it, or to perform any other act or agreement
required to be performed by it, in each case under this Agreement, the Trustee,
without waiving or releasing any obligation or default, may (but shall not be
obligated to) make such payment or perform such other act, or cause the payment
or performance thereof, for the account and at the sole expense of the Grantor.
All amounts so paid by the Trustee and all costs and expenses so incurred shall
constitute obligations

                                       7
<PAGE>   8

of the Grantor secured hereunder and shall be payable under Section 15(b). The
Trustee shall not be liable for any damages resulting from any such payment or
performance.

         SECTION 10. NO ASSUMPTION OF DUTIES; REASONABLE CARE. The rights and
powers conferred on the Trustee hereunder are solely to preserve and protect the
security interest of the Trustee and the Holders of the Notes in and to the
Collateral granted hereby and shall not be interpreted to, and shall not impose
any duties on the Trustee in connection therewith other than those expressly
provided herein or imposed under applicable law. Except as provided by
applicable law or by the Indenture, the Trustee shall be deemed to have
exercised reasonable care in the custody and preservation of the Collateral in
its possession if the Collateral is accorded treatment substantially equal to
that which the Trustee accords similar property held by the Trustee for its own
account, it being understood that the Trustee in its capacity as such shall not
have any responsibility for (a) ascertaining or taking action with respect to
calls, conversions, exchanges, maturities or other matters relative to any
Collateral, whether or not the Trustee has or is deemed to have knowledge of
such matters or (b) taking any necessary steps to preserve rights against any
parties with respect to any Collateral. The Trustee shall be entitled to all the
rights, benefits, privileges and immunities accorded to it under the Indenture.

         SECTION 11. VOTING RIGHTS; DIVIDENDS; ETC.

                  (a) So long as no Event of Default shall have occurred and be
         continuing:

                           (i) The Grantor shall be entitled to exercise or
                  refrain from exercising any and all voting and other
                  consensual rights pertaining to the Security Collateral
                  pledged and assigned by it hereunder, or any part thereof, for
                  any purpose not inconsistent with the terms of this Agreement,
                  the Indenture and the Notes;

                           (ii) The Grantor shall be entitled to receive,
                  retain, and distribute any and all dividends, interest and
                  other distributions paid or distributed in respect of the
                  Security Collateral if and to the extent that the payment
                  thereof is not otherwise prohibited by the terms of the
                  Indenture or the Notes;

                           (iii) The Trustee shall execute and deliver (or cause
                  to be executed and delivered) to the Grantor all such proxies
                  and other instruments as the Grantor may reasonably request
                  for the purpose of enabling the Grantor to exercise the voting
                  and other rights that it is entitled to exercise pursuant to
                  paragraph (i) above and to receive the dividends or interest
                  payments that it is authorized to receive, retain, and
                  distribute pursuant to paragraph (ii) above.

                  (b) Upon the occurrence and during the continuance of an Event
         of Default:

                           (i) All rights of the Grantor (A) to exercise or
                  refrain from exercising the voting and other consensual rights
                  that it would otherwise be entitled to exercise pursuant to
                  Section 11(a)(i) shall, upon notice to the Grantor by the
                  Trustee acting at the direction of the Holders of a majority
                  interest of Outstanding Notes, cease and (B) to receive, the
                  dividends, interest payments, and other

                                       8
<PAGE>   9

                  distributions that it would otherwise be authorized to
                  receive, retain, and distribute pursuant to Section 11(a)(ii)
                  shall automatically cease, and all such rights shall thereupon
                  become vested in the Trustee, which shall thereupon have the
                  sole right to exercise or refrain from exercising such voting
                  and other consensual rights and to receive and hold as
                  Collateral such dividends, interest payments and other
                  distributions as the Holders of a majority in interest of
                  Outstanding Notes shall direct.

                           (ii) All dividends, interest payments, and other
                  distributions that are received by the Grantor contrary to the
                  provisions of paragraph (i) of this Section 11(b) shall be
                  received in trust for the benefit of the Trustee, shall be
                  segregated from other funds of the Grantor and shall be
                  forthwith paid over to the Trustee as Collateral in the same
                  form as so received (with any necessary indorsement).

         SECTION 12. TRANSFERS AND OTHER LIENS; ADDITIONAL EQUITY INTERESTS.

                  (a) The Grantor agrees that it will not (i) sell, assign or
         otherwise dispose of, or grant any option with respect to, any of the
         Collateral of the Grantor if such sale, assignment, disposition or
         grant of option would cause or result in a Default or an Event of
         Default or (ii) create or suffer to exist any Lien on any of the
         Collateral except for Liens created hereunder.

                  (b) The Grantor agrees that it shall cause the Company not to
         issue any Equity Interests in addition to or in substitution for the
         Pledged Interests, unless immediately upon such issuance, such Equity
         Interests is pledged to the Trustee for the benefit of the Holders.

                  (c) Any sale, assignment or other disposition of any of the
         Collateral shall be subject to the Lien created hereunder in favor of
         the Trustee (on its behalf and on behalf of the Holders of the Notes)
         continuing in such Collateral.

         SECTION 13. SECURITY INTEREST ABSOLUTE. The obligations of the Grantor
under this Agreement are independent of the Secured Obligations, and a separate
action or actions may be brought and prosecuted against the Grantor to enforce
this Agreement, irrespective of whether any action is brought against the
Company or whether the Company is joined in any such action or actions. All
rights of the Trustee and the pledge, assignment and security interest
hereunder, and all obligations of the Grantor hereunder, shall be irrevocable,
absolute and unconditional, irrespective of, and the Grantor hereby irrevocably
waives (to the maximum extent permitted by applicable law) any defenses it may
now have or may hereafter acquire in any way relating to, any or all of the
following:

                  (a) any lack of validity or enforceability of the Indenture,
         the Notes, any Security Document or any other agreement or instrument
         relating thereto;

                                       9
<PAGE>   10

                  (b) any change in the time, manner or place of payment of, or
         in any other term of, all or any of the Secured Obligations or any
         other obligations under the Indenture, the Notes or any Security
         Document, or any other amendment or waiver of or any consent to any
         departure from the Indenture, the Notes or any Security Document,
         including, without limitation, any increase in the Secured Obligations
         resulting from the extension of additional credit to the Company, any
         of its Subsidiaries or otherwise;

                  (c) any taking, exchange, release or non-perfection of any
         other collateral, or any taking, release or amendment or waiver of or
         consent to departure from any guaranty, for all or any of the Secured
         Obligations;

                  (d) any manner of application of Collateral, or proceeds
         thereof, to all or any of the Secured Obligations, or any manner of
         sale or other disposition of any Collateral for all or any of the
         Secured Obligations or any other obligations of the Company under or in
         respect of the Indenture, the Notes, and the Security Documents or any
         other assets of the Company or any of its Subsidiaries;

                  (e) any change, restructuring or termination of the corporate,
         partnership or other structure or existence of the Company or any of
         its Subsidiaries; and

                  (f) any other circumstance (including without limitation any
         statute of limitations) that might otherwise constitute a defense
         available to, or a discharge of, the Grantor or a third party grantor
         of a security interest other than the payment in full of the Secured
         Obligations.

         SECTION 14. REMEDIES. If an Event of Default shall have occurred and be
continuing:

                  (a) The Trustee or the majority of the Holders of the Notes
         may, or in the event of an acceleration under Section 502 of the
         Indenture then the Trustee shall, exercise in respect of the
         Collateral, in addition to other rights and remedies provided for
         herein or in the Indenture or otherwise available to it, all the rights
         and remedies of a secured party upon default under the NYUCC (whether
         or not the NYUCC applies to the affected Collateral) and also may (i)
         require the Grantor to, and the Grantor hereby agrees that it will at
         its expense and upon request of the Trustee forthwith, assemble all or
         part of the Collateral as directed by the Trustee and make it available
         to the Trustee at a place to be designated by the Trustee that is
         reasonably convenient to both parties and (ii) without notice except as
         specified below, sell the Collateral or any part thereof in one or more
         parcels at public or private sale, at any of the Trustee's offices or
         elsewhere, for cash, on credit or for future delivery, and upon such
         other terms as commercially reasonable. The Grantor agrees that, to the
         extent notice of sale shall be required by law, at least ten days'
         notice to the Grantor of the time and place of any public sale or the
         time after which any private sale is to be made shall constitute
         reasonable notification. The Trustee shall not be obligated to make any
         sale of Collateral regardless of notice of sale having been given. The
         Trustee may adjourn any public or private sale from time to time by
         announcement at the time and place fixed therefor, and such sale may,
         without further notice, be made at the time and place to which it was
         so adjourned.

                                       10
<PAGE>   11

                  (b) All cash proceeds received by the Trustee in respect of
         any sale of, collection from, or other realization upon all or any part
         of the Collateral be held by the Trustee as collateral for, and/or then
         or at any time thereafter applied (after payment of any amounts payable
         to the Trustee pursuant to Section 15(b)) in whole or in part by the
         Trustee for the ratable benefit of the Holders of the Notes against,
         all or any part of the Secured Obligations in such order as the Trustee
         shall elect. Any surplus of such cash or cash proceeds held by the
         Trustee and remaining after payment in full of all the Secured
         Obligations shall be paid over to the Grantor or to whomsoever else may
         be lawfully entitled to receive such surplus.

                  (c) Notwithstanding the foregoing, the Grantor and the Trustee
         recognize that any disposition of Collateral must be made in accordance
         with any applicable federal or state securities laws. The Grantor
         recognizes that the Trustee may deem it impracticable to effect a
         public sale of all or any part of the Collateral subject to such
         securities laws and that the Trustee may, therefore, determine to make
         one or more private sales of any such Collateral to a restricted group
         of purchasers who will be obligated to agree, among other things, to
         acquire such Collateral for their own account, for investment and not
         with a view to the distribution or resale thereof. The Grantor
         acknowledges that any such private sale may be at prices and on terms
         less favorable than the prices and other terms which might have been
         obtained at a public sale and, notwithstanding the foregoing, agrees
         that such private sale shall be deemed to have been made in a
         commercially reasonable manner and that the Trustee shall have no
         obligation to delay sale of any such securities for the period of time
         necessary to permit the Grantor to register such Collateral for public
         sale under the Securities Act of 1933, as amended.

         SECTION 15. INDEMNITY AND EXPENSES.

                  (a) The Grantor agrees to indemnify, defend and save and hold
         harmless the Trustee and each of its officers, directors, employees,
         agents and advisors (each, an "Indemnified Party") from and against,
         and shall pay on demand, any and all claims, damages, losses,
         liabilities and expenses (including, without limitation, reasonable
         fees and expenses of counsel) that may be incurred by or asserted or
         awarded against any Indemnified Party, in each case arising out of or
         in connection with or resulting from the Trustee's performance as
         Trustee under this Agreement (including, without limitation,
         enforcement of this Agreement), except any such claim, damage, loss,
         liability or expense as may be attributable to its negligence or
         willful misconduct.

                  (b) The Grantor will upon demand pay to the Trustee (i) the
         amount of any and all reasonable out-of-pocket costs and expenses of
         the Trustee, including the reasonable fees, expenses, and disbursements
         of counsel to the Trustee and of any experts and agents, that the
         Trustee may incur in connection with (A) the custody, preservation, use
         or operation of, or the sale of, collection from or other realization
         upon, any of the Collateral or (B) the failure by the Grantor to
         perform or observe any of the provisions hereof; and (ii) all costs and
         expenses of the Trustee and each of the Holders of the Notes in
         connection with the exercise of any of their rights hereunder or the
         enforcement of this Agreement (including, without limitation, the
         reasonable fees and expenses of counsel for

                                       11
<PAGE>   12

         the Trustee and each of the Holders of the Notes with respect thereto),
         whether in any action, suit or litigation, any bankruptcy, insolvency
         or other similar proceeding affecting creditors' rights generally or in
         any negotiated settlement or workout, except in the case of clauses (i)
         and (ii), any such cost, expense, or disbursement as may be
         attributable to the Trustee's negligence or willful misconduct.

                  (c) Without prejudice to the survival of any other agreement
         of the Grantor hereunder, the agreements and obligations of the Grantor
         contained in this Section 16 shall survive the termination of this
         Agreement and the resignation or removal of the Trustee.

         SECTION 16. AMENDMENTS, WAIVERS AND CONSENTS.

                  (a) Any amendment or waiver of any provision of this Agreement
         and any consent to any departure by the Grantor from any provision of
         this Agreement shall be effective only if in writing, signed by the
         Trustee and made or duly given in compliance with all of the terms and
         provisions of the Indenture, and then such waiver or consent shall be
         effective only in the specific instance and for the specific purpose
         for which given. Neither the Trustee nor any Holder of Notes shall be
         deemed, by any act, delay, indulgence, omission or otherwise, to have
         waived any right or remedy hereunder or to have acquiesced in any
         Default or Event of Default or in any breach of any of the terms and
         conditions hereof. Failure of the Trustee or any Holder of Notes to
         exercise, or delay in exercising, any right, power or privilege
         hereunder shall not preclude any other or further exercise thereof or
         the exercise of any other right, power or privilege. A waiver by the
         Trustee or any Holder of Notes of any right or remedy hereunder on any
         one occasion shall not be construed as a bar to any right or remedy
         that the Trustee or such Holder of Notes would otherwise have on any
         future occasion. The rights and remedies herein provided are
         cumulative, may be exercised singly or concurrently and are not
         exclusive of any rights or remedies provided by law.

                  (b) Without the consent of any Holders of the Notes and the
         Grantors, the Trustee may amend or waive any provision of this
         Agreement or consent to any departure by any Grantor from any provision
         hereof, for any of the following purposes:

                           (i) to evidence the succession of another Person to
                  the Company, or any other Grantor, and the assumption by any
                  such successor of the obligations of the Company or such other
                  Grantor contained herein;

                           (ii) to evidence and provide for the appointment of a
                  successor Trustee;

                           (iii) to cure any ambiguity, to correct or supplement
                  any provision in this Agreement that may defective or
                  inconsistent with any other provision of this Agreement or the
                  Indenture, or to make any other provisions with respect to
                  matters or questions arising under this Agreement with shall
                  not be inconsistent with the provisions of this Agreement or
                  the Indenture; provided that, in each

                                       12
<PAGE>   13

                  case, such actions pursuant to this clause shall not
                  materially adversely affect the interests of the Holders; or

                           (iv) to mortgage, pledge, hypothecate or grant of
                  security interest in additional collateral in favor of the
                  Trustee for the benefit of the Holders.

         SECTION 17. NOTICES; ETC. All notices and other communications provided
for hereunder shall be in writing (including telecopier, telegraphic or cable
communication) and, mailed, telecopied, cabled or delivered:

                  (a)      if to the Grantor, at its address at:

                           Bonneville Pacific Corporation
                           c/o El Paso Merchant Energy Holding Company
                           1001 Louisiana Street
                           Houston, Texas 77002
                           Telecopy: (713) 420-3220
                           Attn: John Harrison

                           with copy to:

                           El Paso Corporation
                           1001 Louisiana Street
                           Houston, Texas 77002
                           Telecopy: (713) 420-2813
                           Attn: Andrew Kidd

                  (b)      if to the Trustee, at its Corporate Trust Office
                           referred to in the Indenture;

or, as to any such party, at such other address as shall be designated by such
party in a written notice to each other party complying as to delivery with the
terms of this Section. All such notices and communications shall, when mailed,
telecopied, telegraphed or telexed, be effective when deposited in the mails,
telecopied, or confirmed by telex answerback, respectively, except that notices
and communications to the Trustee shall not be effective until received by the
Trustee. Delivery by telecopier of an executed counterpart of any amendment or
waiver of any provision of this Agreement to be executed and delivered hereunder
shall be effective as delivery of a manually executed counterpart thereof.

         SECTION 18. CONTINUING SECURITY INTEREST. Subject to any collateral
released under Section 16, this Agreement shall create a continuing security
interest in and to the Collateral and shall (a) remain in full force and effect
until the payment in full in cash of the Secured Obligations, (b) be binding
upon the Grantor and its successors and permitted assigns and (c) inure,
together with the rights and remedies of the Trustee hereunder, to the benefit
of, and be enforceable by, the Trustee, the Holders of the Notes and their
respective successors, transferees and assigns. Without limiting the generality
of the foregoing clause (c), the Trustee may assign or otherwise transfer all or
any portion of its rights and obligations under the Indenture and the

                                       13
<PAGE>   14

Notes to any other Person, and such other Person shall thereupon become vested
with all the benefits in respect thereof granted to the Trustee, as the case may
be, herein or otherwise, in each case as and to the extent provided in Section
610 of the Indenture.

         SECTION 19. WAIVERS AND ACKNOWLEDGMENTS.

                  (a) The Grantor hereby waives promptness, diligence, notice of
         acceptance and any other notice with respect to any of the Secured
         Obligations and this Agreement and any requirement that the Trustee or
         any Holder of a Note protect, secure, perfect or insure any Lien or any
         property subject thereto or exhaust any right or take any action
         against the Company or any other Person or any Collateral.

                  (b) The Grantor hereby waives any right to revoke this
         Agreement, and acknowledges that this Agreement is continuing in nature
         and applies to all Secured Obligations, whether existing now or in the
         future.

                  (c) The Grantor acknowledges that it will receive substantial
         direct and indirect benefits from the financing arrangements
         contemplated by the Indenture, the Notes and the Security Documents and
         that the waivers set forth in this Section 19 are knowingly made in
         contemplation of such benefits.

         SECTION 20. SUBROGATION. The Grantor will not exercise any rights that
it may now or hereafter acquire against the Company or any of its Subsidiaries
that arise from the existence, payment, performance or enforcement of the
Grantor's obligations under this Agreement, including, without limitation, any
right of subrogation, reimbursement, exoneration, contribution or
indemnification and any right to participate in any claim or remedy of the
Trustee or any Holders of the Notes against the Company or of its Subsidiaries
or any Collateral, whether or not such claim, remedy or right arises in equity
or under contract, statute or common law, including, without limitation, the
right to take or receive from the Company or any of its Subsidiaries, directly
or indirectly, in cash or other property or by set-off or in any other manner,
payment or security on account of such claim, remedy or right, unless and until
all of the Secured Obligations and all other amounts payable under this
Agreement shall have been paid in full in cash (except that the Grantor may
exercise any such claim, right or remedy solely against, and the Grantor may
take and receive any such amount solely from, amounts permitted to be
distributed or paid on account of Subordinated Indebtedness in accordance with
and subject to the restrictions set forth in Section 1012 of the Indenture). If
any amount shall be paid to the Grantor in violation of the preceding sentence
at any time prior to the later of the payment in full in cash of the Secured
Obligations and all other amounts payable under this Agreement, such amount
shall be held in trust for the benefit of the Trustee and the other Holders of
the Notes and shall forthwith be paid to the Trustee to be credited and applied
to the Secured Obligations and all other amounts payable under this Agreement,
whether matured or unmatured, in accordance with the terms of the Indenture, or
to be held as Collateral for any Secured Obligations or other amounts payable
under this Agreement thereafter arising.

         SECTION 21. RELEASE AND TERMINATION. Upon the payment in full in cash
of the Secured Obligations, the pledge, assignment and security interest granted
hereby shall terminate

                                       14
<PAGE>   15

and all rights to the Collateral shall revert to the Grantor. Upon any such
termination, the Trustee will, at the Grantor's expense, execute and deliver to
the Grantor such documents as the Grantor shall reasonably request to evidence
such termination.

         SECTION 22. AUTHORITY OF THE TRUSTEE.

                  (a) The Trustee shall have and be entitled to exercise all
         powers hereunder that are specifically granted to the Trustee by the
         terms hereof, together with such powers as are reasonably incident
         thereto. The Trustee may perform any of its duties hereunder or in
         connection with the Collateral by or through agents or employees and
         shall be entitled to retain counsel and to act in reliance upon the
         advice of counsel concerning all such matters. Except as otherwise
         expressly provided in this Agreement or the Indenture, neither the
         Trustee nor any director, officer, employee, attorney or agent of the
         Trustee shall be liable to the Grantor for any action taken or omitted
         to be taken by the Trustee, in its capacity as Trustee, hereunder,
         except for its own negligence or willful misconduct, and the Trustee
         shall not be responsible for the validity, effectiveness or sufficiency
         hereof or of any document or security furnished pursuant hereto. The
         Trustee and its directors, officers, employees, attorneys and agents
         shall be entitled to rely on any communication, instrument or document
         believed by it or them to be genuine and correct and to have been
         signed or sent by the proper person or persons.

                  (b) The Grantor acknowledges that the rights and
         responsibilities of the Trustee under this Agreement with respect to
         any action taken by the Trustee or the exercise or non-exercise by the
         Trustee of any option, right, request, judgment or other right or
         remedy provided for herein or resulting or arising out of this
         Agreement shall, as between the Trustee and the Holders of the Notes,
         be governed by the Indenture and by such other agreements with respect
         thereto as may exist from time to time among them, but, as between the
         Trustee and the Grantor, the Trustee shall be conclusively presumed to
         be acting as agent for the Holders of the Notes with full and valid
         authority so to act or refrain from acting, and the Grantor shall not
         be obligated or entitled to make any inquiry respecting such authority.

         SECTION 23. EXECUTION IN COUNTERPARTS. This Agreement may be executed
in any number of counterparts and by different parties hereto in separate
counterparts, each of which when so executed shall be deemed to be an original
and all of which taken together shall constitute one and the same agreement.
Delivery of an executed counterpart of a signature page to this Agreement by
telecopier shall be effective as delivery of a manually executed counterpart of
this Agreement.

         SECTION 24. REINSTATEMENT. This Agreement shall continue to be
effective or be reinstated, as the case may be, if at any time any payment of
any of the Secured Obligations is rescinded or must otherwise be returned by the
Trustee, any Holder of the Notes or by any other Person upon the insolvency,
bankruptcy or reorganization of the Company or otherwise, all as though such
payment had not been made.

                                       15
<PAGE>   16

         SECTION 25. SEVERABILITY. Any provision of this Agreement which is
prohibited or unenforceable in any jurisdiction shall, as to such jurisdiction,
be ineffective to the extent of such prohibition or unenforceability without
invalidating the remaining provisions hereof, and any such prohibition or
unenforceability in any jurisdiction shall not invalidate or render
unenforceable such provision in any other jurisdiction.

         SECTION 26. GOVERNING LAW; ENTIRE AGREEMENT. This Agreement shall be
governed by, and construed in accordance with, the laws of the State of New
York. This Agreement constitutes the entire understanding among the Grantor, the
Trustee and the Holders of the Notes with respect to the subject matter hereof
and supercede any prior agreements, written or oral, with respect thereto.

                         [SIGNATURES BEGIN ON NEXT PAGE]

                                       16
<PAGE>   17

         IN WITNESS WHEREOF, the parties hereto have caused this Agreement to be
duly executed and delivered by its officer thereunto duly authorized as of the
date first above written.

                                           BONNEVILLE PACIFIC CORPORATION

                                           By: /s/ D. T. Field
                                               ---------------------------------
                                           Name: D. T. Field
                                                 -------------------------------
                                           Title: Attorney-in-Fact
                                                  ------------------------------

                                           THE BANK OF NEW YORK, AS TRUSTEE

                                           By: /s/ Marybeth Lewicki
                                               ---------------------------------
                                           Name: Marybeth Lewicki
                                                 -------------------------------
                                           Title: Vice President
                                                  ------------------------------

                                Signature Page-1

<PAGE>   18

                                   SCHEDULE I

                                EQUITY INTERESTS

<Table>
<Caption>
                                                                PERCENTAGE OF
                                                             OUTSTANDING EQUITY
   ISSUER                       TYPE OF INTEREST                   INTEREST
   ------                       ----------------             ------------------
<S>                        <C>                            <C>

East Coast Power L.L.C.    Class A Limited Liability      Class A Limited Liability
                           Company Membership             Company Membership
                           Interest                       Interest representing a .9%
                                                          Sharing Ratio
</Table>

                                   Schedule I

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