=========================================================================== SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 ------------------ FORM 8-A/A ------------------ FOR REGISTRATION OF CERTAIN CLASSES OF SECURITIES PURSUANT TO SECTION 12(b) OR (g) OF THE SECURITIES EXCHANGE ACT OF 1934 ATLANTIC RICHFIELD COMPANY (Exact name of Registrant as specified in its charter) DELAWARE 23-0371610 (State of incorporation or organization) (I.R.S. Employer Identification No.) 333 South Hope Street Los Angeles, California 90071 (Address, including zip code, of principal executive offices) Securities to be registered pursuant to Section 12(b) of the Act: Title of each class Name of each exchange on which to be so registered each class is to be registered Common Stock New York Stock Exchange Purchase Rights If this Form relates to the registration of a class of debt securities and is effective upon filing pursuant to General Instruction A.(c)(1), please check the following box. [ ] If this Form relates to the registration of a class of debt securities and is to become effective simultaneously with the effectiveness of a concurrent registration statement under the Securities Act of 1933 pursuant to General Instruction A.(c)(2), please check the following box. [ ] Securities to be registered pursuant to Section 12(g) of the Act: None (Title of class) =========================================================================== Item 1. Description of Securities to be Registered. At a meeting of the Atlantic Richfield Company (the "Company") Board of Directors on March 31, 1999 the Board approved the amendment of certain terms of the Rights Agreement (the "Rights Agreement") dated as of July 24, 1995, between the Company and First Chicago Trust Company of New York, as Rights Agent. Effective on March 31, 1999, the Company and First Chicago Trust Company of New York, as Rights Agent, amended the Rights Agreement pursuant to the Board's approval in connection with the proposed merger (the "Merger") of Prairie Holdings, Inc., a direct wholly owned subsidiary of BP Amoco p.l.c., with the Company. The amendments add certain definitions and make changes to certain definitions and provisions to cause the provisions of the Rights Agreement not to apply to the Merger and its related transactions and to cause the Rights to cease to be exercisable immediately prior to the Merger. The amendment to the Rights Agreement is attached hereto as Exhibit 4, which is incorporated herein by reference. The foregoing description of the amendments does not purport to be complete and is qualified in its entirety by reference to that Exhibit. Item 2. Exhibits. Item 2 is amended by adding thereto the following: 4. Amendment dated as of March 31, 1999, to the Rights Agreement dated as of July 24, 1995, between Atlantic Richfield Company and First Chicago Trust Company of New York, as Rights Agent. SIGNATURE Pursuant to the requirements of Section 12 of the Securities Exchange Act of 1934, the registrant has duly caused this registration statement to be signed on its behalf by the undersigned, thereunto duly authorized. ATLANTIC RICHFIELD COMPANY, by /s/ Allan L. Comstock Date: April 1, 1999 --------------------------- Name: Allan L. Comstock Title: Vice President and Controller INDEX OF EXHIBITS Page Number in Sequentially Exhibit Numbered Number Title Statement 4. Amendment dated as of March 31, 1999, to the Rights Agreement dated as of July 24, 1995, between Atlantic Richfield Company and First Chicago Trust Company of New York, as Rights Agent.