11. Equity

Equity Offerings

Commencing in November 2012, the Partnership had an At the Market offering program (the “November 2012 ATM”) in place with a financial institution (the “Manager”) which allows the Partnership from time to time, through the Manager as its sales agent, to offer and sell common units representing limited partner interests in the Partnership. Sales of such common units are made by means of ordinary brokers’ transactions on the NYSE at market prices, in block transactions or as otherwise agreed upon by the Manager and the Partnership. The Partnership may also sell common units to the Manager as principal for its own account at a price to be agreed upon at the time of the sale. For any such sales, the Partnership will enter into a separate agreement with the Manager. During the nine months ended September 30, 2013, the Partnership sold an aggregate of 9.3 million common units under the November 2012 ATM, receiving net proceeds of approximately $584.3 million after deducting approximately $9.4 million in manager fees and other third-party expenses. The proceeds from sales were used to fund capital expenditures and for general partnership purposes.

On August 7, 2013, the Partnership entered into an Equity Distribution Agreement with the Manager that established a $400 million At the Market offering program (the “August 2013 ATM”). During the nine months ended September 30, 2013, the Partnership sold an aggregate of 5.9 million common units under the August 2013 ATM, receiving net proceeds of approximately $396.0 million after deducting approximately $4.0 million in manager fees and other third-party expenses. The proceeds from sales were used to fund capital expenditures and for general partnership purposes.

On September 5, 2013, the Partnership, entered into an Equity Distribution Agreement with the Manager that established an At the Market offering program (the “September 2013 ATM”) pursuant to which, the Partnership may sell from time to time through the Manager as its sales agent, common units representing limited partner interests having an aggregate offering price of up to $1 billion. During the nine months ended September 30, 2013, the Partnership sold an aggregate of 0.9 million common units under the September 2013 ATM Agreement, receiving net proceeds of approximately $59.5 million after deducting approximately $0.6 million in manager fees and other third-party expenses. The proceeds from sales were used to fund capital expenditures and for general partnership purposes.

All of the Partnership’s Class B units were issued to and are held by M&R MWE Liberty, LLC, an affiliate of The Energy and Minerals Group (“EMG”), as part of the Partnership’s December 31, 2011 acquisition of the non-controlling interest in MarkWest Liberty Midstream & Resources, L.L.C. (“MarkWest Liberty Midstream”). Approximately four million Class B units converted to common units on July 1, 2013. The remaining Class B units will convert to common units on a one-for-one basis in four equal installments beginning on July 1, 2014 and each of the next three anniversaries of such date.

Distributions of Available Cash and Range of Unit Prices

	Common Unit Price				Distribution Per Common
Quarter Ended	High		Low		Unit		Declaration Date	Record Date	Payment Date
September 30, 2013	$	72.35	$	65.27	$	0.85	October 23, 2013	November 7, 2013	November 14, 2013
June 30, 2013	$	71.20	$	56.90	$	0.84	July 24, 2013	August 6, 2013	August 14, 2013
March 31, 2013	$	61.97	$	51.77	$	0.83	April 25, 2013	May 7, 2013	May 15, 2013
December 31, 2012	$	55.95	$	46.03	$	0.82	January 23, 2013	February 6, 2013	February 14, 2013