8-K

UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

FORM 8-K

CURRENT REPORT
PURSUANT TO SECTION 13 OR 15(d) OF
THE SECURITIES EXCHANGE ACT OF 1934

Date of Report (Date of earliest event reported): February 18, 2013

MARKWEST ENERGY PARTNERS, L.P.

(Exact name of registrant as specified in its charter)

Delaware	001-31239	27-0005456
(State or other jurisdiction of incorporation or organization)	(Commission File Number)	(I.R.S. Employer Identification Number)

1515 Arapahoe Street, Tower 1, Suite 1600, Denver CO 80202

(Address of principal executive offices)

Registrant’s telephone number, including area code: 303-925-9200

Not Applicable.

(Former name or former address, if changed since last report.)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions (see General Instruction A.2. below):

oWritten Communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)

oSoliciting material pursuant to Rule 14a-12 under the Exchange Act (17 CFR 240.14a-12)

oPre-Commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))

oPre-Commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

ITEM 1.01.Entry Into a Material Definitive Agreement.

On February 18, 2013, MarkWest Energy Partners, L.P. (the “Partnership”), through its wholly-owned subsidiary MarkWest Utica Operating Company, L.L.C. (“MarkWest”), and the Energy & Minerals Group, through its affiliate EMG Utica, LLC (“EMG”), entered into an Amended and Restated Limited Liability Company Agreement (the “Amended Utica JV Agreement”) of MarkWest Utica EMG, L.L.C. (the “Utica JV”).  The Utica JV is a joint venture dedicated to engaging in the natural gas midstream business in the Utica Shale formation in and around the state of Ohio.  The Amended Utica JV Agreement defines the rights, obligations, and relationship of MarkWest and EMG with respect to the Utica JV.

Pursuant to the Amended Utica JV Agreement, the aggregate funding commitment of EMG has increased from $500 million to $950 million (the “Minimum EMG Investment”).  As part of this commitment, EMG is required to fund, as needed, all capital required for the Utica JV until such time as EMG has contributed aggregate capital equal to $750 million (the “Tier 1 EMG Contributions”).  Following the funding of the Tier 1 EMG Contributions, MarkWest will have the one time right to elect to fund up to 60% of all capital required for the Utica JV until such time as EMG has contributed aggregate capital equal to the Minimum EMG Investment, and EMG will be required to fund all capital not elected to be funded by MarkWest.  Once EMG has funded the Minimum EMG Investment, MarkWest will be required to fund, as needed, 100% of all capital for the Utica JV until such time as the aggregate capital that has been contributed by MarkWest and EMG equals $2 billion.  After such time, and until the Investment Balances (as defined below) of MarkWest and EMG are in the ratio of 70% and 30%, respectively (the “Equalization Date”), EMG will have the right, but not the obligation, to fund up to 10% of each capital call for the Utica JV, and MarkWest will be required to fund all remaining capital not elected to be funded by EMG.  After the Equalization Date, MarkWest and EMG will have the right, but not the obligation, to maintain their relative interests (based on their respective Investment Balances, as described below) in the Utica JV by funding their pro rata portion of any additional required capital and may also fund additional capital which the other party elects not to fund.  The parties’ respective obligations to contribute capital are subject to capital calls made in accordance with an approved budget of the Utica JV.  The Amended Utica JV Agreement also provides for a special contribution of capital by EMG, and a special distribution of capital to MarkWest, based upon the interim funding that MarkWest previously provided to the Utica JV on behalf of EMG as described in the Partnership’s Current Report on Form 8-K filed on February 5, 2013.  The allocation of available cash generated by the Utica JV did not change, and MarkWest will continue to receive 60% of cash generated by the Utica JV that is available for distribution until the earlier of December 31, 2016 and the date on which MarkWest’s Investment Balance equals 60% of the aggregate Investment Balances of MarkWest and EMG.  After the earlier to occur of those dates, cash generated by the Utica JV that is available for distribution will be allocated to MarkWest and EMG in proportion to their respective Investment Balances.

Under the Amended Utica JV Agreement, MarkWest and EMG each have an “Investment Balance” equal to the amount of capital contributed by that party to the Utica JV.  After EMG has contributed more than $500 million to the Utica JV, and prior to December 31, 2016, EMG’s Investment Balance will also be increased by a quarterly preference applied to the amount of capital contributed by EMG in excess of $500 million.  No preference will accrue after December 31, 2016.

If MarkWest’s Investment Balance does not equal at least 51% of the aggregate Investment Balances of EMG and MarkWest as of December 31, 2016, then EMG may, by written notice delivered to MarkWest by December 15, 2016, require (a “True-Up”) that MarkWest acquire membership interests from EMG so that, following the purchase, MarkWest’s Investment Balance equals 51% of the aggregate Investment Balances of EMG and MarkWest.  The price payable in connection with a True Up would equal the Investment Balance associated with the membership interests so acquired from EMG.   If EMG makes this election, then MarkWest would be required to acquire the membership interests on or prior to March 1, 2017, but effective as of January 1, 2017.  If EMG makes this election and MarkWest does not acquire the membership interests, then EMG may pursue certain remedies, which under certain circumstances may include the removal of MarkWest as the operator of the Utica JV.  If EMG is entitled to make this election but chooses not to do so, then for as long as MarkWest retains all of its membership interests in the Utica JV, if MarkWest’s Investment Balances is less than 50%, MarkWest will be deemed to have an Investment Balance equal to 50% for purposes of the election of managers to the Utica JV and certain member voting rights.

2

Additional modifications in the Amended Utica JV Agreement include, among other things: (i) adjusting the area of mutual interest for the Utica JV’s operations; (ii) adjusting the number of managers so that MarkWest and EMG each designate three managers, subject to adjustment based on changes in the Investment Balances of MarkWest and EMG after the earlier of December 31, 2016 and the date on which MarkWest’s Investment Balance equals at least 60% of the aggregate Investment Balances of MarkWest and EMG; (iii) allowing EMG to pledge its membership interest as collateral for loans meeting certain requirements and affording MWE Operating certain rights to purchase EMG’s interests upon the foreclosure of such loans; (iv) adjusting the tax allocations of certain items of gross income, gains, losses and deductions; and (v) modifying the manner in which proceeds of a liquidation of the Utica JV would be allocated, so that liquidation proceeds would be allocated between MarkWest and EMG in proportion to their respective Investment Balances.

The remaining provisions of the Amended Utica JV Agreement are materially similar to the prior limited liability company agreement of the Utica JV.

ITEM 7.01.Regulation FD Disclosure

On February 21, 2013, the Partnership issued a press release announcing the completion of definitive agreements for the Utica Joint Venture.  A copy of the press release is furnished as Exhibit 99.1 hereto.

ITEM 9.01.Financial Statements and Exhibits.

(d)   Exhibits.

Exhibit No.	Description of Exhibit
99.1	Press Release dated February 21, 2013 announcing completion of definitive agreements for Utica Joint Venture

3

SIGNATURE

Pursuant to the requirements of the Securities and Exchange Act of 1934, the Registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

	MARKWEST ENERGY PARTNERS, L.P.
	(Registrant)
	By:	MarkWest Energy GP, L.L.C.,
		Its General Partner
Date: February 22, 2013	By:	/s/ Nancy K. Buese
		Nancy K. Buese
		Senior Vice President and Chief Financial Officer

4

EX-99.1

Exhibit 99.1

Contact:	Frank Semple, Chairman, President and CEO		Contact:	John Raymond, Managing Partner & CEO
	Nancy Buese, Senior VP and CFO			Jeff Rawls, Managing Director
	Joshua Hallenbeck, VP of Finance/Treasurer			Patrick Wade, Managing Director
Phone:	(866) 858-0482		Phone	(713) 579-5000
E-mail	investorrelations@markwest.com

MarkWest Energy Partners and The Energy & Minerals Group Complete Definitive Agreements for Utica Joint Venture

DENVER—February 21, 2013—MarkWest Energy Partners, L.P. (MarkWest) (NYSE: MWE) and The Energy & Minerals Group (EMG) announced today the completion of the previously announced Amended and Restated Limited Liability Company Agreement (Amended LLC Agreement) for MarkWest Utica EMG, LLC (Utica Joint Venture).  The Utica Joint Venture is dedicated to the development of critical midstream infrastructure on behalf of natural gas producers operating throughout the liquids-rich Utica Shale formation in Ohio.

Under the terms of the Amended LLC Agreement, EMG will increase its initial capital investment in the Utica Joint Venture from $500 million to $950 million.  The additional contributions from EMG provide MarkWest with significant financial flexibility in the timing of its capital contributions to the Utica Joint Venture. The Amended LLC Agreement does not modify the ownership interest levels or quarterly distribution percentages as originally set forth between the parties.

In addition, MarkWest expects to receive a distribution from the Utica Joint Venture substantially equivalent to its short-term contribution by the end of February 2013.

In the past three months, MarkWest has successfully raised $1.5 billion in net proceeds from debt and equity transactions.  In addition, MarkWest is currently undrawn on its $1.2 billion credit facility and has the ability to issue common units under its $600 million continuous equity program.  These transactions, coupled with the execution of the Amended LLC Agreement, provide MarkWest with significant liquidity to fund the majority of its 2013 capital plan.

“We are pleased to announce the expansion of our relationship with EMG in the Utica Shale,” said Frank Semple, Chairman, President and Chief Executive Officer of MarkWest. “The success of our Utica Shale Joint Venture is a direct result of the outstanding drilling results by our producer customers and the execution of our full-service midstream business model in this rapidly developing resource play.  Clearly, we believe that the Utica Joint Venture with EMG is creating significant long-term value for our customers and our investors.”

“Due to the tremendous success of producers operating in the Utica Shale, the scale and scope of the Utica Joint Venture has expanded considerably over the course of the past year.  This transaction addresses the capital requirements associated with the ongoing system expansion.” stated John Raymond, Managing Partner and CEO of EMG.  “We are pleased to further grow and support the relationship we have with the talented people at MarkWest.”

###

About MarkWest Energy Partners, L.P.

1

MarkWest Energy Partners, L.P. is a master limited partnership engaged in the gathering, transportation, and processing of natural gas; the transportation, fractionation, marketing, and storage of natural gas liquids; and the gathering and transportation of crude oil. MarkWest has extensive natural gas gathering, processing, and transmission operations in the southwest, Gulf Coast, and northeast regions of the United States, including the Marcellus Shale, and is the largest natural gas processor and fractionator in the Appalachian region.

This press release includes “forward-looking statements.”  All statements other than statements of historical facts included or incorporated herein may constitute forward-looking statements. Actual results could vary significantly from those expressed or implied in such statements and are subject to a number of risks and uncertainties. Although MarkWest believes that the expectations reflected in the forward-looking statements are reasonable, MarkWest can give no assurance that such expectations will prove to be correct. The forward-looking statements involve risks and uncertainties that affect operations, financial performance, and other factors as discussed in filings with the Securities and Exchange Commission.  Among the factors that could cause results to differ materially are those risks discussed in the periodic reports filed with the SEC, including MarkWest’s Annual Report on Form 10-K for the year ended December 31, 2011 and its Quarterly Reports on Form 10-Q for the quarters ended March 31, 2012, June 30, 2012 and September 30, 2012. You are urged to carefully review and consider the cautionary statements and other disclosures made in those filings, specifically those under the heading “Risk Factors.”  MarkWest does not undertake any duty to update any forward-looking statement except as required by law.

About The Energy & Minerals Group

The Energy & Minerals Group is a highly specialized private equity firm that focuses exclusively on investing across various facets of the global natural resource industry that are integral to the global economy.  EMG has $6.2 Billion of total investor commitments (including co-investments) with in excess of $3.1 Billion deployed across the energy complex since inception. For additional information on EMG, please contact Alexandra Coolidge at 713-579-5029.

Source: MarkWest Energy Partners, L.P.

MarkWest Energy Partners, L.P.

Frank Semple, Chairman, President & CEO

Nancy Buese, Senior VP & CFO

Josh Hallenbeck, VP of Finance & Treasurer

866-858-0482

investorrelations@markwest.com

2