Sec Form 4 Filing - HARRIS JEFFREY @ Kosmos Energy Ltd. - 2011-05-16

FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person HARRIS JEFFREY 2. Issuer Name and Ticker or Trading Symbol Kosmos Energy Ltd. [ KOS] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) X __ Director _____ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) C/O WARBURG PINCUS LLC, 450 LEXINGTON AVE 3. Date of Earliest Transaction (MM/DD/YY) 05/16/2011 (Street) NEW YORK, NY10017 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) __ X __ Form filed by One Reporting Person _____ Form filed by More than One Reporting Person (City) (State) (Zip)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned 1.Title of Security (Instr. 3) 2. Transaction Date (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4) Code V Amount (A) or (D) Price Common Shares 05/16/2011 J( 1 ) 154,379,137 ( 2 ) A $ 0 ( 1 ) 154,379,137 I See Footnotes ( 1 ) ( 2 ) ( 3 )

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned ( e.g. , puts, calls, warrants, options, convertible securities) 1. Title of Derivative Security (Instr. 3) 2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 4. Transaction Code (Instr. 8) 5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5) 6. Date Exercisable and Expiration Date (MM/DD/YY) 7. Title and Amount of Underlying Securities (Instr. 3 and 4) 8. Price of Derivative Security (Instr. 5) 9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4) 10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4) 11. Nature of Indirect Beneficial Ownership (Instr. 4) Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares Series A Convertible Preferred Units $ 0 ( 1 ) 05/16/2011 J( 1 ) 16,129,849 ( 1 ) ( 1 ) Common Shares 87,664,716 $ 0 ( 1 ) 0 I See Footnote ( 4 ) Series B Convertible Preferred Units $ 0 ( 1 ) 05/16/2011 J( 1 ) 10,771,752 ( 1 ) ( 1 ) Common Shares 59,157,300 $ 0 ( 1 ) 0 I See Footnote ( 4 ) Series C Convertible Preferred Units $ 0 ( 1 ) 05/16/2011 J( 1 ) 476,134 ( 1 ) ( 1 ) Common Shares 2,588,876 $ 0 ( 1 ) 0 I See Footnote ( 4 ) C1 Units $ 0 ( 1 ) 05/16/2011 J( 1 ) 1,345,081 ( 1 ) ( 1 ) Common Shares 4,968,245 $ 0 ( 1 ) 0 I See Footnote ( 4 )

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other HARRIS JEFFREY C/O WARBURG PINCUS LLC 450 LEXINGTON AVE NEW YORK, NY10017 X Signatures /s/ Jeffrey A. Harris 05/18/2011 Signature of Reporting Person Date

Explanation of Responses:

( 1 )The common shares, par value $0.01 (the "Common Shares") of Kosmos Energy Ltd. (the "Issuer"), were issued in exchange for the outstanding units in Kosmos Energy Holdings ("KEH") listed in Table II pursuant to the corporate reorganization (the "Corporate Reorganization") in connection with the initial public offering of Common Shares of the Issuer, which units were exchangeable pursuant to the Fourth Amended and Restated Operating Agreement of KEH upon the closing of the initial public offering of the Issuer based on the pre-offering equity value of such units. ( 2 )Reflects the aggregate number of Common Shares directly owned by Warburg Pincus Private Equity VIII, L.P., a Delaware limited partnership ("WPPE VIII"), together with two affiliated limited partnerships (together with WPPE VIII, "WP VIII"), and Warburg Pincus International Partners, L.P., a Delaware limited partnership ("WPIP LP"), together with two affiliated limited partnerships (together with WPIP LP, "WPIP"). ( 3 )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 Member of WP LLC. The Common Shares of the Issuer which WP VIII and WPIP have acquired are reflected as indirectly beneficially owned by Mr. Harris because of his affiliation with the Warburg Pincus entities. Mr. Harris disclaims beneficial ownership with respect to any Common Shares of the Issuer in which he does not have a direct pecuniary interest. ( 4 )Reflects the aggregate number of units of KEH directly owned by WP VIII and WPIP prior to the exchange of such units on May 16, 2011 pursuant to the Corporate Reorganization.

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.

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