Filing Details

SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 (Amendment No. 4)* Chesapeake Energy Corporation ________________________________________________________ (Name of Issuer) Common Stock _______________________________________________________ (Title of Class and Securities) 165167107 _______________________________________________________ (CUSIP Number of Class of Securities) Check the appropriate box to designate the rule pursuant to which this Schedule is filed: /X/ Rule 13d-1(b) / / Rule 13d-1(c) / / Rule 13d-1(d) * The remainder of this cover page shall be filled out for a reporting person's initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter the disclosures provided in a prior page. The information required in the remainder of this cover page shall not be deemed to be "filed" for the purpose of Section 18 of the Securities Exchange Act of 1934 ("Act") or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

(Continued on following page(s))CUSIP No. 165167107 13G _____________________________________________________________________________ (1) NAMES OF REPORTING PERSONS Southeastern Asset Management, Inc. I.D. No. 62-0951781 _____________________________________________________________________________ (2) CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP: (a) (b) X _____________________________________________________________________________ (3) SEC USE ONLY _____________________________________________________________________________ (4) CITIZENSHIP OR PLACE OF ORGANIZATION Tennessee _____________________________________________________________________________ : (5) SOLE VOTING POWER : (Discretionary Accounts) NUMBER OF SHARES BENEFICIALLY : 35,501,011 shares OWNED BY EACH REPORTING PERSON __________________________________________ WITH : (6) SHARED OR NO VOTING POWER 13,907,710 shares (shared) 4,531,741 shares (No Vote) __________________________________________ : (7) SOLE DISPOSITIVE POWER (Discretionary Accounts) : 40,032,752 shares __________________________________________ : (8) SHARED DISPOSITIVE POWER : 13,907,710 shares (Shared) 0 shares (None) _____________________________________________________________________________ (9) AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON (Discretionary & Non-discretionary Accounts) 53,940,462 shares _____________________________________________________________________________ (10) CHECK BOX IF THE AGGREGATE AMOUNT IN ROW 9 EXCLUDES CERTAIN SHARES _____________________________________________________________________________ (11) PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9 7.6 % _____________________________________________________________________________ (12) TYPE OF REPORTING PERSON IA _____________________________________________________________________________ CUSIP No. 20854P109 13G _____________________________________________________________________________ (1) NAMES OF REPORTING PERSONS Longleaf Partners Fund I.D. No. 63-6147721 _____________________________________________________________________________ (2) CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP: (a) (b) X _____________________________________________________________________________ (3) SEC USE ONLY _____________________________________________________________________________ (4) CITIZENSHIP OR PLACE OF ORGANIZATION Citizen of United States _____________________________________________________________________________ : (5) SOLE VOTING POWER : (Discretionary Accounts) NUMBER OF SHARES BENEFICIALLY : None OWNED BY EACH REPORTING PERSON __________________________________________ WITH : 6) SHARED VOTING POWER : 12,561,111 shares (Shared) __________________________________________ : (7) SOLE DISPOSITIVE POWER : None __________________________________________ : (8) SHARED DISPOSITIVE POWER : 12,561,111 shares (Shared) _____________________________________________________________________________ (9) AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 12,561,111 shares _____________________________________________________________________________ (10) CHECK BOX IF THE AGGREGATE AMOUNT IN ROW 9 EXCLUDES CERTAIN SHARES _____________________________________________________________________________ (11) PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW 9 1.8 % _____________________________________________________________________________ (12) TYPE OF REPORTING PERSON IV _____________________________________________________________________________