X0508 4 2023-08-14 0 0001552000 MPLX LP MPLX 0001229767 SURMA JOHN P C/O MPLX LP 200 E. HARDIN STREET FINDLAY OH 45840 1 0 0 0 0 Common Units (Limited Partner Interests) 2023-08-14 4 A 0 1286.033 0.00 A 66732.102 D 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 John P. Surma 2023-08-16