Sec Form 4 Filing - Marathon Petroleum Corp @ MPLX LP - 2015-08-17

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 Marathon Petroleum Corp 2. Issuer Name and Ticker or Trading Symbol MPLX LP [ MPLX] 5. Relationship of Reporting Person(s) to Issuer (Check all applicable) X __ Director X __ 10% Owner _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) 539 S. MAIN STREET 3. Date of Earliest Transaction (MM/DD/YY) 08/17/2015 (Street) FINDLAY, OH45840 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) _____ Form filed by One Reporting Person __ X __ 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 Units (Limited Partner Interests) 08/17/2015 C 36,951,515 ( 1 ) ( 2 ) ( 3 ) A 56,932,134 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 Subordinated Units (Limited Partner Interests) ( 4 ) 08/17/2015 C 36,951,515 ( 1 ) ( 2 ) ( 3 ) ( 4 ) ( 4 ) Common Units 36,951,515 ( 4 ) 0 I See footnotes ( 1 ) ( 2 ) ( 3 )

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Marathon Petroleum Corp 539 S. MAIN STREET FINDLAY, OH45840 X X MPC Investment LLC 539 S. MAIN STREET FINDLAY, OH45840 X X MPLX GP LLC 200 E. HARDIN STREET FINDLAY, OH45840 X MPLX Logistics Holdings LLC 200 E. HARDIN STREET FINDLAY, OH45840 X Signatures /s/ J. Michael Wilder, Vice President, General Counsel and Secretary, Marathon Petroleum Corporation 08/18/2015 Signature of Reporting Person Date /s/ J. Michael Wilder, Vice President, General Counsel and Secretary, MPC Investment LLC 08/18/2015 Signature of Reporting Person Date /s/ J. Michael Wilder, Vice President, General Counsel and Secretary, MPLX GP LLC 08/18/2015 Signature of Reporting Person Date /s/ Molly R. Benson, Assistant Secretary, MPLX Logistics Holdings LLC 08/18/2015 Signature of Reporting Person Date

Explanation of Responses:

( 1 )This Form 4 is filed jointly by Marathon Petroleum Corporation ("MPC"), MPC Investment LLC ("MPC Investment"), MPLX GP LLC (the "General Partner") and MPLX Logistics Holdings LLC ("MPLX Logistics Holdings"). MPC Investment, a direct wholly-owned subsidiary of MPC, owns all of the membership interests in both the General Partner and MPLX Logistics Holdings. Accordingly, the General Partner and MPLX Logistics Holdings are both indirect wholly-owned subsidiaries of MPC. ( 2 )The General Partner owns a 2% general partner interest in the Issuer. MPC Investment owns all of the membership interest in the General Partner and MPC owns all of the membership interest in MPC Investment. Accordingly, MPC and MPC Investment both may be deemed to indirectly beneficially own the securities of the Issuer directly held by the General Partner, but disclaim beneficial ownership except to the extent of their respective pecuniary interests therein. ( 3 )The General Partner directly owns 1,639,525 general partner units, representing its 2% general partner interest in the Issuer. ( 4 )All 36,951,515 issued and outstanding subordinated units representing limited partner interests in the Issuer were converted into Common Units on a one-for-one basis, effective August 17, 2015, upon the expiration of the subordination period as set forth in the Issuer's First Amended and Restated Agreement of Limited Partnership.

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

* 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).

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