UNDERWRITING AGREEMENTUnderwriting Agreement • April 5th, 2010 • Markwest Energy Partners L P • Crude petroleum & natural gas • New York
MarkWest Energy Partners, L.P., a Delaware limited partnership (the “Partnership”), proposes to issue and sell to the underwriters named in Schedule I (the “Underwriters”) attached to this underwriting agreement (this “Agreement”) an aggregate of 4,250,000 common units (the “Firm Units”) representing limited partner interests in the Partnership (“Common Units”). The Partnership also proposes to issue and sell to the Underwriters not more than an additional 637,500 Common Units (the “Additional Units”) if and to the extent that Morgan Stanley & Co. Incorporated, Barclays Capital Inc., UBS Securities LLC and Wells Fargo Securities, LLC, as representatives of the several Underwriters (the “Representatives”), shall have determined to exercise the right to purchase such Additional Units granted to the Underwriters pursuant to Section 2 hereof. The Firm Units and the Additional Units, if purchased, are hereinafter collectively referred to as the “Units.”
