DENVER--(BUSINESS WIRE)--MarkWest Energy Partners LP (NYSE: MWE) announced today that it is commencing a public offering of 8,000,000 common units. MarkWest intends to grant the underwriters a 30-day option to purchase a maximum of 1,200,000 additional common units to cover the underwriters’ sale of additional common units, if any. MarkWest intends to use the net proceeds from the offering and from any exercise of the underwriters’ option to purchase additional common units to partially fund its acquisition of Keystone Midstream Services, LLC, which owns certain gas gathering and processing facilities located in Butler County, Pennsylvania. If MarkWest does not consummate the Keystone Acquisition, it intends to use the net proceeds from the offering and from any exercise of the underwriters’ option for general partnership purposes, including, but not limited to, funding capital expenditures and general working capital.

Morgan Stanley, BofA Merrill Lynch, Barclays, Citigroup, UBS Investment Bank and Wells Fargo Securities are acting as joint book-running managers for the offering. The offering is being made only by means of a prospectus supplement and accompanying base prospectus. A copy of the prospectus supplement and accompanying base prospectus associated with the offering may be obtained from the underwriters as follows: