MARKWEST ENERGY PARTNERS, L.P. 10,000,000 COMMON UNITS REPRESENTING LIMITED PARTNER INTERESTS UNDERWRITING AGREEMENT December 13, 2011Underwriting Agreement • December 19th, 2011 • 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”), for whom you (the “Representatives”) are acting as representatives, an aggregate of 10,000,000 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 1,500,000 Common Units (the “Additional Units” and together with the Firm Units, the “Units”) if and to the extent the Underwriters shall have determined to exercise the right to purchase such Additional Units granted to the Underwriters pursuant to Section 2 of this Agreement.
