Purchase Agreement

and any reference to the Preliminary Offering Circular or the Offering Circular, as the case may be, as amended or supplemented, as of any specified date, shall be deemed to include (i) any

documents filed with the Commission pursuant to Section 13(a), 13(c) or 15(d) of the United States Securities Exchange Act of 1934, as amended (the “Exchange Act”) after the date of the Preliminary Offering Circular or the Offering Circular, as the case may be, and prior to such specified date (excluding information therein that was furnished to (and not filed with) the Commission) and (ii) any Additional Issuer Information (as defined in Section 5(e)) furnished by the Company prior to the completion of the distribution by the Purchasers of the Notes; and all documents filed under the Exchange Act and so deemed to be included in the Preliminary Offering Circular or the Offering Circular, as the case may be, or any amendment or supplement thereto are hereinafter called the “Exchange Act Reports.”  The Exchange Act Reports, when they were or are filed with the Commission, conformed or will conform in all material respects to the applicable requirements of the Exchange Act and the applicable rules and regulations of the Commission thereunder.  The Preliminary Offering Circular or the Offering Circular and any amendments or supplements thereto and the Exchange Act Reports did not and will not, as of their respective dates, contain an untrue statement of a material fact or omit to state a material fact necessary in order to make the statements therein, in the light of the circumstances under which they were made, not misleading; provided, however, that this representation and warranty shall not apply to any statements or omissions made in reliance upon and in conformity with information furnished in writing to the Company by a Purchaser through Goldman, Sachs & Co. expressly for use therein;

(b)            Neither the Company nor any of its subsidiaries has sustained since the date of the latest audited financial statements included in the Offering Circular any material loss or material interference with its business from fire, explosion, flood or other calamity, whether or not covered by insurance, or from any labor dispute or court or governmental action, order or decree, otherwise than as set forth or contemplated in the Offering Circular; and, since the respective dates as of which information is given in the Offering Circular, there has not been any change in the capital stock (other than regular quarterly dividends on the Company’s common stock or pursuant to employee benefit plans or arrangements described in the Exchange Act Reports and in effect on the date hereof) or long-term debt (other than under the Company’s bank credit agreement or uncommitted money market lines of credit in effect on the date hereof) of the Company or any of its subsidiaries, or any material adverse change, or any development involving a prospective material adverse change, in or affecting the general affairs, management, financial position, shareholders’ equity or results of operations of the Company and its subsidiaries taken as a whole, otherwise than as set forth or contemplated in the Offering Circular;

(c)            The Company has been duly incorporated and is validly existing as a corporation in good standing under the laws of the State of Delaware and has the corporate power and authority to own, lease and operate its properties and to conduct its business as described in the Offering Circular and to enter into and perform its obligations under this Agreement; and the Company is duly qualified as a foreign corporation to transact business and is in good standing in each other jurisdiction in which such qualification is required, whether by reason of the ownership or leasing of property or the conduct of business, except where the failure so to qualify or to be in good standing would not result in a material adverse change in the condition, financial or otherwise, or in the earnings, business affairs or business prospects of the Company and its subsidiaries considered as one enterprise, whether or not arising in the ordinary course of business (a “Material Adverse Effect”);

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(d)            Each “significant subsidiary” (as such term is defined in Rule 1-02 of Regulation S-X under the Exchange Act) of the Company as of the date hereof (each a “Designated Subsidiary” and, collectively, the “Designated Subsidiaries”) is identified on Schedule II hereto, has been duly formed or incorporated and is validly existing as a corporation or other business entity in good standing under the laws of the jurisdiction of its formation or incorporation, has the corporate, partnership or company power and authority to own, lease and operate its properties and to conduct its business as described in the Offering Circular and is duly qualified as a foreign corporation or other business entity to transact business and is in good standing in each other jurisdiction in which such qualification is required, whether by reason of the ownership or leasing of property or the conduct of business, except where the failure so to qualify or to be in good standing would not result in a Material Adverse Effect; all of the issued and outstanding capital stock or equivalent equity interests of each Designated Subsidiary have been duly authorized and validly issued, are fully paid and non-assessable and (except for directors’ qualifying shares or shares representing an immaterial equity interest that are required under the laws of any foreign jurisdiction to be owned by others, and except as set forth in the Offering Circular) are owned by the Company, directly or through subsidiaries, free and clear of any security interest, mortgage, pledge, lien, encumbrance or claim; and none of the outstanding shares of capital stock or equivalent equity interests of the Designated Subsidiaries were issued in violation of any preemptive or similar rights arising by operation of law, or under the charter, by-laws or other comparable organizational documents of any Designated Subsidiary or under any agreement to which the Company or any Designated Subsidiary is a party;

(e)            Each of the Company and its subsidiaries has (i) generally satisfactory title to its oil and gas properties, title investigations having been carried out by the Company or its subsidiaries in accordance with the practice in the oil and gas industry in the areas in which the Company and its subsidiaries operate, (ii) good and marketable title to all other real property owned by it to the extent necessary to carry on its business and (iii) good and marketable title to all personal property owned by it, in each case free and clear of all liens, encumbrances and defects except such as are described in the Offering Circular or such as do not materially affect the value of the properties of the Company and its subsidiaries, considered as one enterprise, and do not interfere with the use made and proposed to be made of such properties, by the Company and its subsidiaries, considered as one enterprise; and all of the leases and subleases material to the business of the Company and its subsidiaries, considered as one enterprise, and under which the Company or any of its subsidiaries holds properties described in the Offering Circular, are in full force and effect, and neither the Company nor any of its subsidiaries has any notice of any material claim of any sort that has been asserted by anyone adverse to the rights of the Company or its subsidiaries under any of the leases or subleases mentioned above, or affecting or questioning the rights of the Company or any subsidiary thereof to the continued possession of the leased or subleased premises under any such lease or sublease;

(f)             The authorized, issued and outstanding capital stock of the Company is as set forth in the Offering Circular in the column entitled “Actual” under the caption “Capitalization” (except as indicated in the notes thereto with respect to any subsequent issuances pursuant to employee or director benefit plans referred to in the Offering Circular or pursuant to the exercise of convertible securities or options referred to in the Offering Circular); and the shares of issued and outstanding capital stock of the Company have been duly authorized and validly issued and are fully paid and nonassessable, and none of the outstanding shares of capital

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stock of the Company was issued in violation of the preemptive or other similar rights of any securityholder of the Company;

(g)            The Notes, and notes having terms substantially identical to the Notes other than the payment of additional interest (the “Exchange Notes”) issuable in exchange for the Notes in an exchange offer (the “Exchange Offer”) pursuant to the Registration Rights Agreement (as defined in Section 1(h) below), have been duly authorized and, when issued and delivered pursuant to this Agreement (in the case of the Notes) or, if and when issued and delivered pursuant to the Registration Rights Agreement (in the case of the Exchange Notes) and duly authenticated pursuant to the Indenture, will have been duly executed, authenticated, issued and delivered and will constitute valid and legally binding obligations of the Company entitled to the benefits provided by the Indenture; the Indenture has been duly authorized by the Company and upon execution and delivery by the parties thereto will (assuming the due authorization, execution and delivery by the Trustee) constitute a valid and legally binding instrument of the Company, enforceable against the Company in accordance with its terms, except as limited by bankruptcy, insolvency, moratorium, fraudulent transfer, reorganization and other similar laws of general application affecting the rights and remedies of creditors and by general equity principles (regardless of whether enforceability is considered in a proceeding in equity or at law);

(h)            This Agreement has been duly authorized, executed and delivered by the Company, and the exchange and registration rights agreement (the “Registration Rights Agreement”), to be dated as of the Time of Delivery (as defined below), has been duly authorized by the Company and, when duly executed and delivered by the Company and the other parties thereto (assuming the due authorization, execution and delivery by each party thereto other than the Company), will be the valid and legally binding obligation of the Company, enforceable against the Company in accordance with its terms, except as limited by bankruptcy, insolvency, moratorium, fraudulent transfer, reorganization and other similar laws of general application affecting the rights and remedies of creditors and by general equity principles (regardless of whether enforceability is considered in a proceeding in equity or at law) and, as to rights of indemnification and contribution, subject to principles of public policy or federal or state securities laws relating thereto;

(i)             None of the transactions contemplated by this Agreement (including, without limitation, the use of the proceeds from the sale of the Notes) will violate or result in a violation of Section 7 of the Exchange Act, or any regulation promulgated thereunder, including, without limitation, Regulations T, U, and X of the Board of Governors of the Federal Reserve System;

(j)             Prior to the date of this Agreement, neither the Company nor any of its affiliates has taken any action which is designed to or which has constituted or which reasonably might have been expected to cause or result in stabilization or manipulation of the price of any security of the Company in connection with the offering of the Notes;

(k)            Neither the Company nor any of its subsidiaries is in violation of its charter, by-laws or other governing documents, as applicable, or in default in the performance or observance of any obligation, agreement, covenant or condition contained in any contract, indenture, mortgage, deed of trust, loan or credit agreement, note, lease or other agreement or instrument to which the Company or its subsidiaries is a party or by which any of them may be bound, or to which any of the property or assets of the Company or its subsidiaries is subject

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(collectively, “Agreements and Instruments”) except for such violations or defaults that have not resulted or would not result in a Material Adverse Effect; and the execution, delivery and performance of this Agreement, the Indenture and the Notes and any other agreement or instrument entered into or issued or to be entered into or issued by the Company in connection with the transactions contemplated hereby or thereby or in the Offering Circular (including the Registration Rights Agreement) and the consummation of the transactions contemplated herein and therein and in the Offering Circular (including the issuance and sale of the Notes and the use of the proceeds from the sale of the Notes as described in the Offering Circular under the caption “Use of Proceeds”) and compliance by the Company with its obligations hereunder do not and will not, whether with or without the giving of notice or passage of time or both, conflict with or constitute a breach of, or default or a Repayment Event (as defined below) under, or result in the creation or imposition of any lien, charge or encumbrance upon any property or assets of the Company or its subsidiaries pursuant to, the Agreements and Instruments (including, without limitation, Section 13.2(d) of the Share Purchase Agreement), except for such conflicts, breaches, Repayment Events, defaults, liens, charges or encumbrances that, singly or in the aggregate, have not resulted or would not result in a Material Adverse Effect, nor will such action result in any violation of the provisions of any applicable law, statute, rule, regulation, judgment, order, writ or decree of any government, government instrumentality or court, domestic or foreign, having jurisdiction over the Company or its subsidiaries or any of their assets or properties, except for such violations that, singly or in the aggregate, have not resulted or would not result in a Material Adverse Effect, or any violation of the provisions of the charter or by-laws of the Company or the charter, by-laws or other comparable organizational documents of any of its subsidiaries; as used herein, a “Repayment Event” means any event or condition which gives the holder of any note, debenture or other evidence of indebtedness (or any person acting on such holder’s behalf) the right to require the repurchase, redemption or repayment of all or a portion of such indebtedness by the Company or its subsidiaries;

(l)             No consent, approval, authorization, order, registration or qualification of or with any such court or governmental agency or body is required for the issue and sale of the Notes or the consummation by the Company of the transactions contemplated by this Agreement or the Indenture, except for the filing and effectiveness of one or more registration statements by the Company with the Commission pursuant to the United States Securities Act of 1933, as amended (the “Act”) pursuant to the Registration Rights Agreement, the qualification of the Indenture under the Trust Indenture Act of 1939 (“Trust Indenture Act”) and such consents, approvals, authorizations, registrations or qualifications as may be required under state securities or Blue Sky laws in connection with the purchase and distribution of the Notes by the Purchasers;

(m)           The statements set forth in the Offering Circular under the caption “Description of the Notes”, insofar as they purport to constitute a summary of the terms of the Notes, under the caption “Certain United States Federal Income Tax Considerations” insofar as they purport to describe the provisions of the laws and documents referred to therein and under the caption “Underwriting”, insofar as they purport to describe the provisions of this Agreement referred to therein, are accurate and fair in all material respects;

(n)            Except as disclosed in the Offering Circular, there is no action, suit or proceeding before or by any court or governmental agency or body, domestic or foreign, now pending, or, to the knowledge of the Company, threatened, against or affecting the Company or any subsidiary thereof which might reasonably be expected to result in a Material Adverse Effect, or

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which might reasonably be expected to materially and adversely affect the consummation of the transactions contemplated by this Agreement (including the transactions contemplated by the Registration Rights Agreement) or the performance by the Company of its obligations hereunder;

(o)            When the Notes are issued and delivered pursuant to this Agreement, no Notes will be of the same class (within the meaning of Rule 144A under the Act) as securities which are listed on a national securities exchange registered under Section 6 of the Exchange Act or quoted in a U.S. automated inter-dealer quotation system;

(p)            The Company is subject to Section 13 or 15(d) of the Exchange Act;

(q)            The Company is not, and after giving effect to the offering and sale of the Notes, will not be an “investment company” or an entity “controlled” by an “investment company,” as such terms are defined in the United States Investment Company Act of 1940, as amended (the “Investment Company Act”);

(r)             Neither the Company nor any person acting on its behalf (other than the Purchasers, for whom the Company makes no representation) has offered or sold the Notes by means of any general solicitation or general advertising within the meaning of Rule 502(c) under the Act or, with respect to Notes sold outside the United States to non-U.S. persons (as defined in Rule 902 under the Act), by means of any directed selling efforts within the meaning of Rule 902 under the Act, and the Company, any affiliate of the Company and any person acting on its or their behalf (other than the Purchasers, for whom the Company makes no representation) have complied with and will implement the “offering restrictions” within the meaning of such Rule 902 to the extent applicable to them;

(s)            Within the preceding six months, neither the Company nor any other person acting on its behalf has offered or sold to any person any Notes, or any securities of the Company of the same or a similar class as the Notes, other than Notes offered or sold to the Purchasers hereunder and the 2015 Notes (as defined in the Offering Circular); and the Company will take reasonable precautions designed to insure that any offer or sale, direct or indirect, in the United States or to any U.S. person (as defined in Rule 902 under the Act) of any Notes or any substantially similar security issued by the Company, within six months subsequent to the date on which the distribution of the Notes has been completed (as notified to the Company by Goldman, Sachs & Co. or, in the absence of any such notification, such date shall be deemed to be 20 days after the Time of Delivery), is made under restrictions and other circumstances reasonably designed not to affect the status of the offer and sale of the Notes in the United States and to U.S. persons contemplated by this Agreement as transactions exempt from the registration provisions of the Act (it being acknowledged that the Company may conduct an exchange offer with respect to, or otherwise cause to be registered with the Commission for resale by the holders, the 2015 Notes in accordance with the exchange and registration rights agreement relating thereto);

(t)             PricewaterhouseCoopers LLP, who have audited certain financial statements of the Company and its subsidiaries and have audited the Company’s internal control over financial reporting and management’s assessment thereof as of December 31, 2004 and who have audited certain financial statements of Northrock and its subsidiaries, are an independent registered public accounting firm with respect to each of the Company and Northrock within the

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meaning of the Act and the rules and regulations thereunder adopted by the Commission and the Public Accounting Oversight Board (United States);

(u)            The Company maintains a system of internal control over financial reporting (as such term is defined in Rule
13a-15(f) of the Exchange Act) that complies with the requirements of the Exchange Act and has been designed by the Company’s principal executive officer and principal financial officer, or under their supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles; and based on the Company’s evaluation of its internal control over financial reporting under the framework in Internal Control—Integrated Framework issued by the Committee of Sponsoring Organizations of the Treadway Commission, the Company’s management concluded that its internal control over financial reporting was effective as of December 31, 2004;

(v)            Since December 31, 2004, the date of the latest audited financial statements of the Company incorporated by reference in the Offering Circular, there has been no change in the Company’s internal control over financial reporting that has materially affected, or is reasonably likely to materially affect, the Company’s internal control over financial reporting;

(w)           The Company maintains disclosure controls and procedures (as such term is defined in Rule 13a-15(e) of the Exchange Act) that comply with the requirements of the Exchange Act, such disclosure controls and procedures have been designed to ensure that material information relating to the Company, including its consolidated subsidiaries, is made known to the Company’s principal executive officer and principal financial officer by others within those entities and such disclosure controls and procedures are effective to ensure that the information required to be disclosed by the Company in the reports that it files or submits under the Exchange Act is recorded, processed, summarized and reported within the time periods specified in Commission rules and forms;

(x)             The historical financial statements of the Company, together with the related schedules and notes, included in the Offering Circular present fairly the financial position of the Company and its consolidated subsidiaries at the dates indicated and the statements of operations, shareholders’ equity and cash flows of the Company and its consolidated subsidiaries for the periods specified; and said financial statements have been prepared in conformity with generally accepted accounting principles in the United States (“GAAP”) applied on a consistent basis throughout the periods involved, except as noted therein;

(y)            To the knowledge of the Company, (i) the historical financial statements of Northrock, together with the related schedules and notes, included in the Offering Circular present fairly the financial position of Northrock and its consolidated subsidiaries at the dates indicated and the statements of operations, shareholders’ equity and cash flows of Northrock and its consolidated subsidiaries for the periods specified and (ii) said financial statements have been prepared in conformity with GAAP applied on a consistent basis throughout the periods involved, except as noted therein;

(z)             The pro forma financial information included in the Offering Circular has been prepared on a basis consistent with the historical financial statements from which it has been derived, includes all material adjustments to the historical financial information required by Rule 11-02 of Regulation S-X under the Act and the Exchange Act to reflect the transactions

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described in the Offering Circular, gives effect to assumptions made on a reasonable basis and fairly presents the transactions described in the Offering Circular;

(aa)          The Company and its subsidiaries possess such permits, licenses, approvals, consents and other authorizations (collectively, “Governmental Licenses”) issued by the appropriate federal, state, local or foreign regulatory agencies or bodies necessary to conduct the business now operated by them, except where the failure to possess such Governmental Licenses, would not, singly or in the aggregate, have a Material Adverse Effect; the Company and its subsidiaries are in compliance with the terms and conditions of all such Governmental Licenses, except where the failure so to comply would not, singly or in the aggregate, have a Material Adverse Effect; all of the Governmental Licenses are valid and in full force and effect, except where the invalidity of such Governmental Licenses or the failure of such Governmental Licenses to be in full force and effect would not have a Material Adverse Effect; and neither the Company nor any of its subsidiaries has received any notice of proceedings relating to the revocation or modification of any such Governmental Licenses which, singly or in the aggregate, if the subject of an unfavorable decision, ruling or finding, would reasonably be expected to result in a Material Adverse Effect;

(bb)          The Company and its subsidiaries have filed all necessary federal, state and foreign income and franchise tax returns or have timely requested extensions thereof and have paid all taxes shown as due thereon or made adequate reserve or provision therefor; and other than tax deficiencies which the Company or any subsidiary is contesting in good faith and for which the Company or such subsidiary has provided adequate reserves, there is no tax deficiency that has been asserted against the Company or any subsidiary that would individually or in the aggregate have a Material Adverse Effect;

(cc)          Except as described in the Offering Circular and except for such matters as would not, singly or in the aggregate, result in a Material Adverse Effect, (A) neither the Company nor any of its subsidiaries is in violation of any federal, state, local or foreign statute, law, rule, regulation, ordinance, code, policy or rule of common law or any judicial or administrative interpretation thereof, including any judicial or administrative order, consent, decree or judgment, relating to pollution or protection of human health, the environment (including, without limitation, ambient air, surface water, groundwater, land surface or subsurface strata) or wildlife, including, without limitation, laws and regulations relating to the release or threatened release of chemicals, pollutants, contaminants, wastes, toxic substances, hazardous substances, petroleum or petroleum products (collectively, “Hazardous Materials”) or to the manufacture, processing, distribution, use, treatment, storage, disposal, transport or handling of Hazardous Materials (collectively, “Environmental Laws”), (B) the Company and its subsidiaries have all permits, authorizations and approvals required under any applicable Environmental Laws and are each in compliance with their requirements, (C) there are no pending or, to the knowledge of the Company, threatened administrative, regulatory or judicial actions, suits, demands, demand letters, claims, liens, notices of noncompliance or violation, investigations or proceedings relating to any Environmental Law against the Company or any of its subsidiaries and (D) there are no events or circumstances that might reasonably be expected to form the basis of an order for clean-up or remediation, or an action, suit or proceeding by any private party or governmental body or agency, against or affecting the Company or any of its subsidiaries relating to Hazardous Materials or Environmental Laws;

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(dd)          No labor dispute with the employees of the Company or its subsidiaries exists or, to the knowledge of the Company, is imminent, which, in either case, may reasonably be expected to result in a Material Adverse Effect; and

(ee)          Subject to compliance by the Purchasers with the representations, warranties and agreements set forth in Section 3 and Annex I, it is not necessary in connection with the offer, sale and delivery of the Notes to the Purchasers and the Purchasers’ subsequent sales to QIBs (as defined below) or pursuant to Annex I in the manner contemplated by this Agreement and the Offering Circular to register the Notes under the Act or to qualify the Indenture under the Trust Indenture Act.

2.              Subject to the terms and conditions herein set forth, the Company agrees to issue and sell to each of the Purchasers, and each of the Purchasers agrees, severally and not jointly, to purchase from the Company, at a purchase price of 98.125% of the principal amount thereof, plus accrued interest, if any, from September 23, 2005 to the Time of Delivery hereunder, the principal amount of Notes set forth opposite the name of such Purchaser in Schedule I hereto.

3.              Upon the authorization by you of the release of the Notes, the several Purchasers propose to offer the Notes for sale upon the terms and conditions set forth in this Agreement and the Offering Circular and each Purchaser hereby represents and warrants to, and agrees with the Company that:

(a)            It will offer and sell the Notes only to:  (i) persons who it reasonably believes are “qualified institutional buyers” (“QIBs”) within the meaning of Rule 144A under the Act in transactions meeting the requirements of Rule 144A or (ii) upon the terms and conditions set forth in Annex I to this Agreement;

(b)            It is an institutional “accredited investor” within the meaning of Rule 501 under the Act; and

(c)            It will not offer or sell the Notes by any form of general solicitation or general advertising, including but not limited to the methods described in Rule 502(c) under the Act.

4.              (a)  The Notes to be purchased by each Purchaser hereunder will be represented by one or more definitive global Notes in book-entry form which will be deposited by or on behalf of the Company with The Depository Trust Company (“DTC”) or its designated custodian.  The Company will deliver the Notes to Goldman, Sachs & Co., for the account of each Purchaser, against payment by or on behalf of such Purchaser of the purchase price therefor by wire transfer to the account of the Company of same day funds, by causing DTC to credit the Notes to the account of Goldman, Sachs & Co. at DTC.  The time and date of such delivery and payment shall be 9:30 a.m., New York City time, on September 23, 2005 or such other time and date as Goldman, Sachs & Co. and the Company may agree upon in writing.  Such time and date are herein called the “Time of Delivery”.

(b)            The documents to be delivered at the Time of Delivery by or on behalf of the parties hereto pursuant to Section 7 hereof, including the cross-receipt for the Notes and any additional documents requested by the Purchasers pursuant to Section 7(j) hereof, will be delivered at such time and date at the offices of Baker Botts L.L.P., 910 Louisiana, Houston, Texas 77002 (the “Closing Location”), and the Notes will be delivered to the Trustee as

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custodian for DTC, all at the Time of Delivery.  A meeting will be held at the Closing Location at 5:00 p.m., Houston time, on the New York Business Day next preceding the Time of Delivery, at which meeting the final drafts of the documents to be delivered pursuant to the preceding sentence will be available for review by the parties hereto.  For the purposes of this Section 4, “New York Business Day” shall mean each Monday, Tuesday, Wednesday, Thursday and Friday which is not a day on which banking institutions in New York are generally authorized or obligated by law or executive order to close.

5.              The Company agrees with each of the Purchasers:

(a)            To prepare the Offering Circular in a form approved by you; to make no amendment or any supplement to the Offering Circular which shall be reasonably disapproved by you promptly after reasonable notice thereof; and to furnish you with copies thereof;

(b)            Promptly from time to time to take such action as you may reasonably request to qualify the Notes for offering and sale under the securities laws of such jurisdictions as you may request and to comply with such laws so as to permit the continuance of sales and dealings therein in such jurisdictions for so long as may be necessary to complete the distribution of the Notes, provided that in connection therewith the Company shall not be required to qualify as a foreign corporation or to file a general consent to service of process in any jurisdiction or to qualify as a dealer in securities in any U.S. jurisdiction in which it is not so qualified or to subject itself to taxation in respect of doing business in any jurisdiction in which it is not otherwise so subject;

(c)            To furnish the Purchasers with copies of each amendment or supplement to the Offering Circular and additional written and electronic copies of the Offering Circular and such amendments or supplements in such quantities as you may from time to time reasonably request, and if, at any time prior to the earlier of the effectiveness of a registration statement filed in accordance with the Registration Rights Agreement or the expiration of nine months after the date of the Offering Circular, any event shall have occurred as a result of which the Offering Circular as then amended or supplemented would include an untrue statement of a material fact or omit to state any material fact necessary in order to make the statements therein, in the light of the circumstances under which they were made when such Offering Circular is delivered, not misleading, or, if for any other reason it shall be necessary or desirable during such same period to amend or supplement the Offering Circular, to notify you and upon your request to prepare and furnish without charge to each Purchaser and to any dealer in Notes as many written and el