Ownership Submission
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 OF SECURITIES

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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(Print or Type Responses)
1. Name and Address of Reporting Person *
CLARK JANET F
  2. Issuer Name and Ticker or Trading Symbol
MARATHON OIL CORP [MRO]
5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)
_____ Director _____ 10% Owner
__X__ Officer (give title below) _____ Other (specify below)
Executive V.P. and CFO
(Last)
(First)
(Middle)
C/O MARATHON OIL CORPORATION, 5555 SAN FELIPE ROAD
3. Date of Earliest Transaction (Month/Day/Year)
06/30/2011
(Street)

HOUSTON, TX 77056
4. If Amendment, Date Original Filed(Month/Day/Year)
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 (Month/Day/Year) 2A. Deemed Execution Date, if any (Month/Day/Year) 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
Marathon Oil Corporation Common Stock 06/30/2011   J(1)   28,434 A $ 0 237,043 D  

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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 (Month/Day/Year) 3A. Deemed Execution Date, if any (Month/Day/Year) 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
(Month/Day/Year)
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
Employee Stock Option (Right to Buy) $ 16.708 06/30/2011   J(2)     13,334 01/16/2005(3) 01/16/2014 Common Stock 13,334 $ 0 0 D  
Employee Stock Option (Right to Buy) $ 10.47 06/30/2011   J(2)   12,694   01/16/2007 01/16/2014 Common Stock 12,694 $ 0 12,694 D  
Employee Stock Option (Right to Buy) $ 23.825 06/30/2011   J(2)     117,800 05/25/2006(4) 05/25/2015 Common Stock 117,800 $ 0 0 D  
Employee Stock Option (Right to Buy) $ 14.93 06/30/2011   J(2)   112,168   05/25/2008 05/25/2015 Common Stock 112,168 $ 0 112,168 D  
Employee Stock Option (Right to Buy) $ 37.818 06/30/2011   J(2)     60,400 06/01/2007(5) 06/01/2016 Common Stock 60,400 $ 0 0 D  
Employee Stock Option (Right to Buy) $ 23.69 06/30/2011   J(2)   57,491   06/01/2009 06/01/2016 Common Stock 57,491 $ 0 57,491 D  
Employee Stock Option (Right to Buy) $ 61.05 06/30/2011   J(2)     47,800 05/30/2008(6) 05/30/2017 Common Stock 47,800 $ 0 0 D  
Employee Stock Option (Right to Buy) $ 38.25 06/30/2011   J(2)   45,509   05/30/2010 05/30/2017 Common Stock 45,509 $ 0 45,509 D  
Employee Stock Option (Right to Buy) $ 54.36 06/30/2011   J(2)     42,400 02/27/2009(7) 02/27/2018 Common Stock 42,400 $ 0 0 D  
Employee Stock Option (Right to Buy) $ 34.06 06/30/2011   J(2)   40,337   02/27/2011 02/27/2018 Common Stock 40,337 $ 0 40,337 D  
Employee Stock Option (Right to Buy) $ 23.82 06/30/2011   J(2)(8)     112,900 02/25/2010(9) 02/25/2019 Common Stock 112,900 $ 0 0 D  
Employee Stock Option (Right to Buy) $ 14.92 06/30/2011   J(2)(8)   131,697   02/25/2011(10) 02/25/2019 Common Stock 131,697 $ 0 131,697 D  
Employee Stock Option (Right to Buy) $ 29.17 06/30/2011   J(2)(8)     100,300 02/24/2011(11) 02/24/2020 Common Stock 100,300 $ 0 0 D  
Employee Stock Option (Right to Buy) $ 18.28 06/30/2011   J(2)(8)   138,590   02/24/2011(12) 02/24/2020 Common Stock 138,590 $ 0 138,590 D  
Employee Stock Option (Right to Buy) $ 49.18 06/30/2011   J(8)     75,200 02/23/2012(13) 02/23/2021 Common Stock 75,200 $ 0 0 D  
Employee Stock Option (Right to Buy) $ 30.81 06/30/2011   J(8)   119,836   02/23/2012(14) 02/23/2021 Common Stock 119,836 $ 0 119,836 D  

Reporting Owners

Reporting Owner Name / Address Relationships
 Director  10% Owner  Officer  Other
CLARK JANET F
C/O MARATHON OIL CORPORATION
5555 SAN FELIPE ROAD
HOUSTON, TX 77056
      Executive V.P. and CFO  

Signatures

 Yvonne R. Kunetka, Attorney-in-Fact for Janet F. Clark   07/05/2011
**Signature of Reporting Person Date

Explanation of Responses:

* If the form is filed by more than one reporting person, see Instruction 4(b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
(1) In connection with the spin-off of Marathon Petroleum Corporation on June 30, 2011 by Marathon Oil Corporation ("MRO"), MRO restricted stock awards of MRO officers or employees, who continued as officers or employees of MRO immediately after the spin-off, were replaced with adjusted MRO restricted stock awards, each of which will generally preserve the value of the original award determined as of the distribution date.
(2) In connection with the spin-off of Marathon Petroleum Corporation("MPC") on June 30, 2011 by Marathon Oil Corporation ("MRO"), outstanding MRO stock options that are vested, whether held by a current or former officer or employee of MRO or MPC were adjusted, so that the holders hold stock options to purchase both MRO common stock and MPC common stock. The MRO and MPC stock options received, when combined, will generally preserve the instrinsic value of each original stock option grant and the ratio of the exercise price to the fair market value of MRO common stock on the distribution date.
(3) Vested in cumulative installments on January 1, 2005, 2006 and 2007, respectively.
(4) Vested in cumulative installments on May 25, 2006, 2007 and 2008, respectively.
(5) Vested in cumulative installments on June 1, 2007, 2008 and 2009, respectively.
(6) Vested in cumulative installments on May 30, 2008, 2009 and 2010, respectively.
(7) Vested in cumulative installments on February 27, 2009, 2010 and 2011, respectively.
(8) In connection with the spin-off of Marathon Petroleum Corporation on June 30, 2011 by Marathon Oil Corporation ("MRO"), outstanding MRO stock options that are not vested and are held by MRO officers or employees, who continued as officers or employees of MRO immediately after the spin-off, were replaced with adjusted MRO stock options to purchase MRO common stock, which will generally preserve the intrinsic value of each original stock option grant and the ratio of the exercise price to the fair market value of MRO common stock on the distribution date.
(9) Vests in cumulative annual installments of 75,266 and 37,634 shares on February 25, 2011 and 2012, respectively.
(10) Vests in cumulative annual installments of 71,644 and 60,053 shares on February 25, 2011 and 2012, respectively.
(11) Vests in three cumulative annual installments of 33,433, 33,433 and 33,434 on February 24, 2011, 2012, and 2013, respectively.
(12) Vests in three cumulative annual installments of 31,836, 53,376 and 53,378 shares on February 24, 2011, 2012, and 2013, respectively.
(13) Vests in three cumulative annual installments of 25,066, 25,067 and 25,067 on February 23, 2012, 2013, and 2014, respectively.
(14) Vests in three cumulative annual installments of 39,944, 39,946 and 39,946 on February 23, 2012, 2013, and 2014, respectively.

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