X0203 3 2011-05-11 0 0001509991 Kosmos Energy Ltd. KOS 0001220634 HARRIS JEFFREY C/O WARBURG PINCUS LLC 450 LEXINGTON AVE NEW YORK NY 10017 1 0 0 0 Series A Convertible Preferred Units Common Shares 87664716 I See Footnotes Series B Convertible Preferred Units Common Shares 59157300 I See Footnotes Series C Convertible Preferred Units Common Shares 2588876 I See Footnotes C1 Units Common Shares 4968245 I See Footnotes The securities underlying the derivative securities reported herein are issuable pursuant to the corporate reorganization (the "Corporate Reorganization") that will be completed simultaneously with, or prior to, the closing (the "Closing") of the initial public offering of common shares, par value $0.01 (the "Common Shares") of Kosmos Energy Ltd. (the "Issuer") in exchange for the outstanding units of Kosmos Energy Holdings ("KEH"), which units are exchangeable pursuant to the Fourth Amended and Restated Operating Agreement of KEH upon the Closing based on the pre-offering equity value of such units. Pursuant to the Corporate Reorganization, Warbur Pincus Private Equity VIII, L.P., a Delaware limited partnership ("WPPE VIII," and together with two affiliated partnerships, "WP VIII"), and Warburg Pincus International Partners, L.P., a Delaware limited partnership ("WPIP LP," and together with two affiliated partnerships, "WPIP"), have the right to acquire as of the date of this filing 154,379,137 Common Shares of the Issuer in connection with the Closing, which is expected to occur on May 16, 2011. Warburg Pincus Partners, LLC, a New York limited liability company ("WP Partners") and direct subsidiary of Warburg Pincus & Co., a New York general partnership ("WP"), is the sole general partner of WPPE VIII and WPIP LP. WP is the managing member of WP Partners. WP VIII and WPIP are managed by Warburg Pincus LLC, a New York limited liability company ("WP LLC"). Charles R. Kaye and Joseph P. Landy are Managing General Partners of WP and Managing Members and Co-Presidents of WP LLC. Mr. Harris is a Partner of WP and a Managing Director and a Member of WP LLC. The Common Shares of the Issuer which WP VIII and WPIP have the right to acquire are reflected as indirectly beneficially owned by Mr. Harris because of his affiliation with the Warburg Pincus entities. Mr. Harris disclaims benefical ownership with respect to any Common Shares of the Issuer in which he does not have a direct pecuninary interest. /s/ Jeffrey A. Harris 2011-05-11