Common use of Capitalization of the Partnership Clause in Contracts

Capitalization of the Partnership. As of the date hereof, the issued and outstanding limited partner interests of the Partnership consist of 140,981,844 Common Units, 22,640,000 Class A Units and 15,963,511 Class B Units, as such terms are defined in the Third Amended and Restated Agreement of Limited Partnership of the Partnership (as the same has been and may be amended or restated at or prior to the date hereof, the “Partnership Agreement”). All outstanding Common Units, Class A Units and Class B Units and the limited partner interests represented thereby have been duly authorized and validly issued in accordance with the Partnership Agreement and are fully paid (to the extent required under the Partnership Agreement) and nonassessable (except as such nonassessability may be affected by Sections 17-607 and 17-804 of the Delaware LP Act and as otherwise described in the Prospectus). As of the date hereof, MarkWest Hydrocarbon owns 8,900,000 Class A Units and (ii) MarkWest Energy GP owns 13,740,000 Class A Units, in each case free and clear of all liens, encumbrances, security interests, equities, charges or claims (“Liens”), except as may arise under the Amended and Restated Credit Agreement dated as of July 1, 2010 (as supplemented and amended through the date hereof, the “Credit Agreement”) among the Partnership, Xxxxx Fargo Bank, National Association, as administrative agent, RBC Capital Markets Corporation, as syndication agent, and the other parties named therein, or as described in the Disclosure Package and the Prospectus.

Capitalization of the Partnership. As of the date hereof, the issued and outstanding limited partner interests of the Partnership consist of 140,981,844 184,036,767 Common Units, 22,640,000 Class A Units and 15,963,511 11,972,634 Class B Units, as such terms are defined in the Third Amended and Restated Agreement of Limited Partnership of the Partnership (as the same has been and may be amended or restated at or prior to the date hereof, the “Partnership Agreement”). All outstanding Common Units, Class A Units and Class B Units and the limited partner interests represented thereby have been duly authorized and validly issued in accordance with the Partnership Agreement and are fully paid (to the extent required under the Partnership Agreement) and nonassessable (except as such nonassessability may be affected by Sections 17-607 and 17-804 of the Delaware LP Act and as otherwise described in the Prospectus). As of the date hereof, MarkWest Hydrocarbon owns 8,900,000 Class A Units and (ii) MarkWest Energy GP owns 13,740,000 Class A Units, in each case free and clear of all liens, encumbrances, security interests, equities, charges or claims (“Liens”), except as may arise under the Amended and Restated Credit Agreement dated as of July 1, 2010 (as supplemented and amended through the date hereof, the “Credit Agreement”) among the Partnership, Xxxxx Fargo Bank, National Association, as administrative agent, RBC Capital Markets Corporation, as syndication agent, and the other parties named therein, or as described in the Disclosure Package and the Prospectus.

Capitalization of the Partnership. As of the date hereof, the issued and outstanding limited partner interests of the Partnership consist of 140,981,844 161,447,706 Common Units, 22,640,000 Class A Units and 15,963,511 15,963,512 Class B Units, as such terms are defined in the Third Amended and Restated Agreement of Limited Partnership of the Partnership (as the same has been and may be amended or restated at or prior to the date hereof, the “Partnership Agreement”). All outstanding Common Units, Class A Units and Class B Units and the limited partner interests represented thereby have been duly authorized and validly issued in accordance with the Partnership Agreement and are fully paid (to the extent required under the Partnership Agreement) and nonassessable (except as such nonassessability may be affected by Sections 17-607 and 17-804 of the Delaware LP Act and as otherwise described in the Prospectus). As of the date hereof, MarkWest Hydrocarbon owns 8,900,000 Class A Units and (ii) MarkWest Energy GP owns 13,740,000 Class A Units, in each case free and clear of all liens, encumbrances, security interests, equities, charges or claims (“Liens”), except as may arise under the Amended and Restated Credit Agreement dated as of July 1, 2010 (as supplemented and amended through the date hereof, the “Credit Agreement”) among the Partnership, Xxxxx Fargo Bank, National Association, as administrative agent, RBC Capital Markets Corporation, as syndication agent, and the other parties named therein, or as described in the Disclosure Package and the Prospectus.

Capitalization of the Partnership. As of the date hereofhereof and immediately prior to the issuance of Units by the Partnership, the issued and outstanding limited partner interests of the Partnership consist of 140,981,844 75,160,105 Common Units, Units and 22,640,000 Class A Units and 15,963,511 Class B Units, as such terms are defined in the Third Amended and Restated Agreement of Limited Partnership of the Partnership (as the same has been and may be amended or restated at or prior to the date hereofapplicable Closing Date, the “Partnership Agreement”). All outstanding Common Units, Class A Units and Class B A Units and the limited partner interests represented thereby have been duly authorized and validly issued in accordance with the Partnership Agreement and are fully paid (to the extent required under the Partnership Agreement) and nonassessable (except as such nonassessability may be affected by Sections 17-607 and 17-804 of the Delaware LP Act and as otherwise described in the Prospectus). As of the date hereof, MarkWest Hydrocarbon owns 8,900,000 Class A Units and (ii) MarkWest Energy GP owns 13,740,000 Class A Units, in each case free and clear of all liens, encumbrances, security interests, equities, charges or claims (“Liens”), except as may arise under the Amended and Restated Credit Agreement dated as of July 1, 2010 (as supplemented and amended through the date hereof, the “Credit Agreement”) among the Partnership, Xxxxx Fargo Bank, National Association, as administrative agent, RBC Capital Markets Corporation, as syndication agent, and the other parties named therein, or as described in the Pricing Disclosure Package and the Prospectus.

Capitalization of the Partnership. As of the date hereofhereof and immediately prior to the issuance of Units by the Partnership, the issued and outstanding limited partner interests of the Partnership consist of 140,981,844 66,545,872 Common Units, Units and 22,640,000 Class A Units and 15,963,511 Class B Units, as such terms are defined in the Third Amended and Restated Agreement of Limited Partnership of the Partnership (as the same has been and may be amended or restated at or prior to the date hereofapplicable Closing Date, the “Partnership Agreement”). All outstanding Common Units, Class A Units and Class B A Units and the limited partner interests represented thereby have been duly authorized and validly issued in accordance with the Partnership Agreement and are fully paid (to the extent required under the Partnership Agreement) and nonassessable (except as such nonassessability may be affected by Sections 17-607 and 17-804 of the Delaware LP Act and as otherwise described in the Prospectus). As of the date hereof, MarkWest Hydrocarbon owns 8,900,000 Class A Units and (ii) MarkWest Energy GP owns 13,740,000 Class A Units, in each case free and clear of all liens, encumbrances, security interests, equities, charges or claims (“Liens”), except as may arise under the Amended and Restated Credit Agreement Agreement, dated as of July 1February 20, 2010 2008 (as supplemented and amended through by the date hereofFirst Amendment thereto dated January 28, 2009, the “Credit Agreement”) ), among the Partnership, Xxxxx Fargo Bank, National AssociationRoyal Bank of Canada, as administrative agent, RBC Capital Markets Corporation, as syndication and collateral agent, and the other parties named therein, or as described in the Pricing Disclosure Package and the Prospectus.

Capitalization of the Partnership. As of the date hereofhereof and immediately prior to the issuance of Units by the Partnership, the issued and outstanding limited partner interests of the Partnership consist of 140,981,844 71,439,687 Common Units, Units and 22,640,000 Class A Units and 15,963,511 Class B Units, as such terms are defined in the Third Amended and Restated Agreement of Limited Partnership of the Partnership (as the same has been and may be amended or restated at or prior to the date hereofapplicable Closing Date, the “Partnership Agreement”). All outstanding Common Units, Class A Units and Class B A Units and the limited partner interests represented thereby have been duly authorized and validly issued in accordance with the Partnership Agreement and are fully paid (to the extent required under the Partnership Agreement) and nonassessable (except as such nonassessability may be affected by Sections 17-607 and 17-804 of the Delaware LP Act and as otherwise described in the Prospectus). As of the date hereof, MarkWest Hydrocarbon owns 8,900,000 Class A Units and (ii) MarkWest Energy GP owns 13,740,000 Class A Units, in each case free and clear of all liens, encumbrances, security interests, equities, charges or claims (“Liens”), except as may arise under the Amended and Restated Credit Agreement dated as of July 1, 2010 (as supplemented and amended through the date hereof, the “Credit Agreement”) among the Partnership, Xxxxx Fargo Bank, National Association, as administrative agent, RBC Capital Markets Corporation, as syndication agent, and the other parties named therein, or as described in the Pricing Disclosure Package and the Prospectus.

Capitalization of the Partnership. As of the date hereof, the issued and outstanding limited partner interests of the Partnership consist of 140,981,844 146,900,733 Common Units, 22,640,000 Class A Units and 15,963,511 Class B Units, as such terms are defined in the Third Amended and Restated Agreement of Limited Partnership of the Partnership (as the same has been and may be amended or restated at or prior to the date hereof, the “Partnership Agreement”). All outstanding Common Units, Class A Units and Class B Units and the limited partner interests represented thereby have been duly authorized and validly issued in accordance with the Partnership Agreement and are fully paid (to the extent required under the Partnership Agreement) and nonassessable (except as such nonassessability may be affected by Sections 17-607 and 17-804 of the Delaware LP Act and as otherwise described in the Prospectus). As of the date hereof, MarkWest Hydrocarbon owns 8,900,000 Class A Units and (ii) MarkWest Energy GP owns 13,740,000 Class A Units, in each case free and clear of all liens, encumbrances, security interests, equities, charges or claims (“Liens”), except as may arise under the Amended and Restated Credit Agreement dated as of July 1, 2010 (as supplemented and amended through the date hereof, the “Credit Agreement”) among the Partnership, Xxxxx Fargo Bank, National Association, as administrative agent, RBC Capital Markets Corporation, as syndication agent, and the other parties named therein, or as described in the Disclosure Package and the Prospectus.