MarkWest Energy Partners LP - 2011-12-14

The company is commencing a public offering of 8,000,000 common units. The partnership 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.

Citigroup, BofA Merrill Lynch, Barclays Capital, Morgan Stanley, UBS Investment Bank and Wells Fargo Securities are acting as joint book-running managers for the offering.