MarkWest Energy Partners Announces Filing of Definitive Proxy Statement

MarkWest Energy Partners, L.P. (the "Partnership") MWE today announced that it has filed a definitive proxy statement and prospectus with the U.S. Securities and Exchange Commission regarding the pending merger pursuant to which the Partnership would become a wholly owned subsidiary of MPLX LP ("MPLX") MPLX. A special meeting of the common unitholders has been set to approve the previously announced Agreement and Plan of Merger, dated as of July 11, 2015, by and among the Partnership, MPLX, MPLX GP LLC, the general partner of MPLX, Sapphire Holdco LLC, a wholly owned subsidiary of MPLX, and, for certain limited purposes, Marathon Petroleum Corporation. The Partnership's special meeting of common unitholders will be held on Tuesday, December 1, 2015, at 9:00 a.m. Mountain Standard Time at the Partnership's offices at 1515 Arapahoe Street, Tower 1, Suite 1600, Denver, Colorado 80202. The Partnership urges unitholders to submit their proxy as promptly as possible, either by telephone, via the internet or by marking, signing and dating the proxy card that will be provided to unitholders along with the proxy statement and prospectus. All holders of record of the Partnership's common units as of the close of business on October 5, 2015 will be entitled to receive notice of the special meeting and to vote their common units either in person or by proxy at the special meeting. A proxy statement and prospectus for the special meeting will be mailed to the common unitholders of the Partnership on or about October 30, 2015. MarkWest Energy Partners, L.P. is a master limited partnership that owns and operates midstream services related businesses. MarkWest has a leading presence in many natural gas resource plays including the Marcellus Shale, Utica Shale, Huron/Berea Shale, Haynesville Shale, Woodford Shale and Granite Wash formation where it provides midstream services to its producer customers.