1 EXHIBIT 3 SECOND AMENDMENT TO RIGHTS AGREEMENT This Second Agreement, dated as of April 26, 1996 (the "Amendment"), is between MESA Inc., a Texas corporation (the "Company"), and American Stock Transfer and Trust Company (the "Rights Agent"), W I T N E S S E T H: WHEREAS, the Company and the Rights Agent are parties to a Rights Agreement dated as of July 6, 1995 and amended by a First Amendment dated as of July 20, 1995 (as so amended, the "Agreement"); and WHEREAS, pursuant to Section 27 of the Agreement, the Company and the Rights Agent desire to amend the Agreement set forth below. NOW, THEREFORE, in consideration of the premises and the mutual agreements herein set forth, the parties hereby agree as follows: Section 1. Defined Terms. Terms defined in the Rights Agreement shall have the same meaning when used in this Amendment. Section 2. Amendments to Definitions. (a) The definition of "Acquiring Person" in Section 1 of the Agreement is amended to add the following as a new fourth paragraph: Notwithstanding anything contained in this Agreement to the contrary, neither DNR-MESA Holdings, L.P., a Texas limited partnership ("DNR"), nor any of its Affiliates or Associates shall become or be an Acquiring Person solely by virtue of either (i) the execution, delivery and performance of either that certain Stock Purchase Agreement dated April 26, 1996 between DNR and the Company, as it may be amended from time to time hereafter (such agreement, as so amended, being herein called the "DNR Agreement") or of the Ancillary Documents (as defined in the DNR Agreement); or (ii) the consummation of the Transaction (as defined in the DNR Agreement); or (iii) without limiting the generality of clauses (i) and (ii) above, the beneficial ownership by any of such Persons of shares of Common Stock as a result of their beneficial ownership of shares of (A) Series B Preferred Stock acquired by DNR pursuant to the DNR Agreement including, without limitation, shares acquired at the "First Closing" or the "Second Closing" (in Page 4 2 each case as defined in the DNR Agreement); (B) Series A Preferred Stock issued in exchange for Series B Preferred Stock; and (C) Series A Preferred Stock and Series B Preferred Stock issued as dividends; unless and until such time as any such Person, together with its Affiliates and Associates, is then the Beneficial Owner of 10% or more of the shares of Common Stock then outstanding (including, without limitation, by virtue of Beneficial Ownership referenced in clause (i), (ii) or (iii) above) and either (x) such Person shall then purchase or otherwise become the Beneficial Owner of any additional shares of Common Stock or (y) any other Person who is the Beneficial Owner of any shares of Common Stock shall become an Affiliate or Associate of DNR. (b) New definitions of "Series A Preferred Stock" and "Series B Preferred Stock" are hereby added to Section 1 of the Agreement as follows: "Series A Preferred Stock" shall mean the Series A 8% Cumulative Convertible Preferred Stock, par value $.01 per share, of the Company. "Series B Preferred Stock" shall mean the Series B 8% Cumulative Convertible Preferred Stock, par value $.01 per share, of the Company. Section 3. Severability. If any term, provision, covenant or restriction of this Amendment is held by a court of competent jurisdiction or other authority to be invalid, void or unenforceable, the remainder of the terms, provisions, covenants and restrictions of this Amendment shall remain in full force and effect and shall in no way be affected, impaired or invalidated. Section 4. Governing Law. This Amendment shall be deemed to be a contract made under the laws of the State of Texas and for all purposes shall be governed by and construed in accordance with the laws of such State applicable to contracts made and to be performed entirely within such State. Section 5. Counterparts. This Amendment may be executed in any number of counterparts and each of such counterparts shall for all purposes be deemed to be an original, and all such counterparts shall together constitute but one and the same instrument. Section 6. Effect of Amendment. Except as expressly modified herein, the Agreement shall remain in full force and effect. Page 5 3 IN WITNESS WHEREOF, the parties hereto have caused this Amendment to be duly executed all as of the day and year first above written. MESA INC. By /s/ Stephen K. Gardner ---------------------- Name: Stephen K. Gardner Title: Vice President and Chief Financial Officer AMERICAN STOCK TRANSFER AND TRUST COMPANY By /s/ Herbert J. Lemmer --------------------- Name: Herbert J. Lemmer Title: Vice President