X0306 4 2021-12-09 0 0001552000 MPLX LP MPLX 0001067429 Beall Pamela K.M. C/O MPLX LP 200 E. HARDIN STREET FINDLAY OH 45840 1 0 0 0 Common Units (Limited Partner Interests) 2021-12-09 4 A 0 319.969 0.00 A 43246.969 D Common Units (Limited Partner Interests) 10000 I By Revocable Trust By Pamela K. M. Beall Trustee U.T.A. dated 12/26/16 f.b.o. Pamela K. M. Beall, et. al. 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 Pamela K.M. Beall 2021-12-13