Sec Form 4 Filing - Marathon Petroleum Corp @ MPLX LP - 2017-09-01

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) 09/01/2017 (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) 09/01/2017 A 18,511,134 ( 1 ) ( 2 ) ( 3 ) A 118,090,823 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

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 X MPLX Holdings Inc. 539 S. MAIN ST. FINDLAY, OH45840 X Signatures /s/ Molly R. Benson, Vice President, Corporate Secretary and Chief Compliance Officer, Marathon Petroleum Corporation 09/05/2017 Signature of Reporting Person Date /s/ Molly R. Benson, Vice President, Corporate Secretary and Chief Compliance Officer, MPC Investment LLC 09/05/2017 Signature of Reporting Person Date /s/ Molly R. Benson, Vice President, Corporate Secretary and Chief Compliance Officer, MPLX GP LLC 09/05/2017 Signature of Reporting Person Date /s/ Molly R. Benson, Assistant Secretary, MPLX Logistics Holdings LLC 09/05/2017 Signature of Reporting Person Date /s/ Molly R. Benson, Director and Secretary, MPLX Holdings Inc. 09/05/2017 Signature of Reporting Person Date

Explanation of Responses:

( 1 )This Form 4 is filed jointly by Marathon Petroleum Corporation ("MPC"), MPC Investment LLC ("MPCI"), MPLX GP LLC (the "GP"), MPLX Logistics Holdings LLC ("Logistics") and MPLX Holdings Inc. ("Holdings"). MPCI, a direct wholly-owned subsidiary of MPC, owns all of the membership interests in both the GP and Logistics and all of the shares of stock of Holdings. Accordingly, the GP, Logistics and Holdings are all indirect wholly-owned subsidiaries of MPC. ( 2 )Pursuant to the Membership Interests and Shares Contributions Agreement among the Issuer, Logistics, Holdings, the GP and MPCI, on 9/1/2017, MPCI agreed to contribute: the membership interests of Lincoln Pipeline LLC, which holds a 35% interest in Illinois Extension Pipeline Company, L.L.C.; the membership interests of MPL Louisiana Holdings LLC, which holds a 40.7% interest in LOOP LLC; a 58.52% interest in LOCAP LLC; and a 24.51% interest in Explorer Pipeline Company, to the Issuer for $420 million in cash and equity consideration valued at $630 million, consisting of: (i) 13,719,017 common units issued to the GP, (ii) 3,350,893 common units issued to Logistics, (iii) 1,441,224 common units issued to Holdings and (iv) 377,778 general partner units issued to the GP. The units issued were calculated by dividing $630 million by $33.3529, the simple average of the 10 day trading volume weighted average price of a common unit for the 10 trading days ending 8/31/2017. ( 3 )The GP directly owns 8,306,911 general partner units, representing its 2% general partner interest in the Issuer. MPCI owns all of the membership interest in the GP and MPC owns all of the membership interest in MPCI. Accordingly, MPC and MPCI both may be deemed to indirectly beneficially own the securities of the Issuer directly held by the GP, but disclaim beneficial ownership except to the extent of their respective pecuniary interests therein.

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

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