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 *
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 (Month/Day/Year)
03/01/2017
(Street)

FINDLAY, OH 45840
4. If Amendment, Date Original Filed(Month/Day/Year)
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 (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
Common Units (Limited Partner Interests) 03/01/2017   A   12,960,376 (1) (2) (3) A (3) 99,579,689 I See Footnotes (1) (2) (3)

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

Reporting Owners

Reporting Owner Name / Address Relationships
 Director  10% Owner  Officer  Other
Marathon Petroleum Corp
539 S. MAIN STREET
FINDLAY, OH 45840
  X   X    
MPC Investment LLC
539 S. MAIN STREET
FINDLAY, OH 45840
  X   X    
MPLX GP LLC
200 E. HARDIN STREET
FINDLAY, OH 45840
  X      
MPLX Logistics Holdings LLC
200 E. HARDIN STREET
FINDLAY, OH 45840
  X   X    
MPLX Holdings Inc.
539 S. MAIN ST.
FINDLAY, OH 45840
  X      

Signatures

 /s/ Molly R. Benson, Vice President, Corporate Secretary and Chief Compliance Officer, Marathon Petroleum Corporation   03/03/2017
**Signature of Reporting Person Date

 /s/ Molly R. Benson, Vice President, Corporate Secretary and Chief Compliance Officer, MPC Investment LLC   03/03/2017
**Signature of Reporting Person Date

 /s/ Molly R. Benson, Vice President, Corporate Secretary and Chief Compliance Officer, MPLX GP LLC   03/03/2017
**Signature of Reporting Person Date

 /s/ Molly R. Benson, Assistant Secretary, MPLX Logistics Holdings LLC   03/03/2017
**Signature of Reporting Person Date

 /s/ Molly R. Benson, Director and Secretary, MPLX Holdings Inc.   03/03/2017
**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) This Form 4 is filed jointly by Marathon Petroleum Corporation ("MPC"), MPC Investment LLC ("MPC Investment"), MPLX GP LLC (the "General Partner"), MPLX Logistics Holdings LLC ("MPLX Logistics") and MPLX Holdings Inc. ("MPLX Holdings"). MPC Investment, a direct wholly-owned subsidiary of MPC, owns all of the membership interests in both the General Partner and MPLX Logistics and all of the shares of stock of MPLX Holdings. Accordingly, the General Partner, MPLX Logistics and MPLX Holdings are indirect wholly-owned subsidiaries of MPC.
(2) The General Partner directly owns 7,636,916 general partner units, representing its 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) Pursuant to the Membership Interests Contributions Agreement among the Issuer, MPLX Logistics, MPLX Holdings, the General Partner and MPC Investment, on March 1, 2017, MPC Investment agreed to contribute the outstanding membership interests in Hardin Street Transportation LLC, Woodhaven Cavern LLC and MPLX Terminals LLC through a series of intercompany contributions to the Issuer for approximately $1.511 billion in cash and equity consideration valued at approximately $504 million, consisting of: (i) 9,197,900 common units issued to the General Partner, (ii) 2,630,427 common units issued to MPLX Logistics, (iii) 1,132,049 common units issued to MPLX Holdings and (iv) 264,497 general partner units issued to the General Partner. The common units and general partner units issued were calculated by dividing $503,750,000 by $38.0911, the simple average of the volume weighted average price of a common unit for the 10 trading days ending February 28, 2017.

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