X0306 4 2019-07-30 0 0001552000 MPLX LP MPLX 0001490987 Goff Gregory James C/O MPLX LP 200 E. HARDIN STREET FINDLAY OH 45840 1 0 0 0 Common Units (Limited Partner Interests) 2019-07-30 4 A 0 340928.151 A 389801.46 D On July 30, 2019 (the "Effective Time"), pursuant to the Agreement and Plan of Merger, dated as of May 7, 2019 (the "Merger Agreement"), by and among the Issuer, Andeavor Logistics LP ("ANDX"), Tesoro Logistics GP, LLC, MPLX GP LLC and MPLX MAX LLC ("Merger Sub"), Merger Sub merged with and into ANDX (the "Merger"), with ANDX surviving the Merger as a wholly owned subsidiary of the Issuer. Pursuant to the Merger Agreement, at the Effective Time, each common unit representing a limited partner interest in ANDX held by the Reporting Person was converted into the right to receive 1.135 common units (the "Public Unitholder Exchange Ratio") representing limited partner interests in the Issuer (such conversion, the "Common Unit Conversion"). As a result of the Common Unit Conversion, the Reporting Person received 193,490.151 common units representing limited partnership interests in the Issuer. The closing price of common units representing limited partner interests in the Issuer ("MPLX Common Units") on July 29, 2019, which was the last complete trading day prior to the Effective Time, was $28.51 as reported on the New York Stock Exchange. Pursuant to the Merger Agreement, each phantom unit of ANDX held by the Reporting Person was converted, at the Effective Time, into a phantom unit denominated in common units representing limited partner interests in the Issuer (each, a "Converted MPLX Phantom Unit"), with the number of such common units subject to each Converted MPLX Phantom Unit equal to the product of (x) the number of common units representing limited partnership interests in ANDX subject to such phantom units of ANDX held by the Reporting Person immediately prior to Effective Time multiplied by (y) the Public Unitholder Exchange Ratio (such conversion, the "Phantom Unit Conversion"). As a result of the Phantom Unit Conversion, the Reporting Person received 147,438 phantom units in respect of MPLX Common Units. All reported amounts are estimated as of August 1, 2019 based on preliminary information with respect to the Merger. Final amounts will be reported in a subsequent filing. The Reporting Person is a Director of MPLX GP LLC, the general partner of the Issuer. The Issuer is managed by the directors and executive officers of MPLX GP LLC. /s/ Molly R. Benson, Attorney-in-Fact for Gregory James Goff 2019-08-01