X0306 4 2015-09-15 0 0001513965 American Midstream Partners, LP AMID 0001638285 Magnolia Infrastructure Partners, LLC C/O ARCLIGHT CAPITAL PARTNERS, LLC 200 CLARENDON STREET, 55TH FLOOR BOSTON MA 02117 1 0 1 0 0001526603 American Midstream GP, LLC ATTENTION: WILLIAM B. MATHEWS 1400 16TH STREET, SUITE 310 DENVER CO 80202 1 0 1 0 0001575227 High Point Infrastructure Partners, LLC C/O ARCLIGHT CAPITAL PARTNERS, LLC 200 CLARENDON STREET, 55TH FLOOR BOSTON MA 02117 1 0 1 0 0001441290 ArcLight Capital Holdings, LLC C/O ARCLIGHT CAPITAL PARTNERS, LLC 200 CLARENDON STREET, 55TH FLOOR BOSTON MA 02117 1 0 1 0 0001502945 ArcLight Capital Partners, LLC 200 CLARENDON STREET, 55TH FLOOR BOSTON MA 02117 1 0 1 0 0001502553 ARCLIGHT ENERGY PARTNERS FUND V, L.P. C/O ARCLIGHT CAPITAL PARTNERS, LLC 200 CLARENDON STREET, 55TH FLOOR BOSTON MA 02117 1 0 1 0 0001405456 Revers Daniel R C/O ARCLIGHT CAPITAL PARTNERS, LLC 200 CLARENDON STREET, 55TH FLOOR BOSTON MA 02117 1 0 1 0 Common Units 2015-09-15 4 J 0 618921 11.31 A Common Units 618921 618921 D Represents common units representing limited partnership interests of the Issuer (the "Common Units") held directly by Magnolia Infrastructure Partners, LLC ("Magnolia"). Represents Common Units purchased by Magnolia in the Issuer's underwritten public offering of 7,500,000 Common Units, which closed on September 15, 2015. Represents the aggregate number of Common Units held after the acquisition of Common Units reported in Column 5 of this line item. ArcLight Capital Holdings, LLC ("ArcLight Holdings") is the sole manager and member of ArcLight Capital Partners, LLC ("ArcLight Partners"). ArcLight Partners is the investment adviser to ArcLight Energy Partners Fund V, L.P. ("Fund V" and together with ArcLight Holdings and ArcLight Partners, the "ArcLight Entities"). ArcLight Holdings is the manager of the general partner of Fund V. Mr. Revers is a manager of ArcLight Holdings and a managing partner of ArcLight Partners and has certain voting and dispositive rights as a member of ArcLight Partners' investment committee. Fund V indirectly owns Magnolia and, through indirectly controlled subsidiaries, Fund V owns approximately 90% of the ownership interest in HPIP, which in turn owns 95% of the General Partner. As a result, the ArcLight Entities and Mr. Revers may be deemed to indirectly beneficially own the securities of the Issuer held by Magnolia, HPIP and the General Partner, but disclaim beneficial ownership except to the extent of their respective pecuniary interests therein. /s/ Daniel R. Revers, MAGNOLIA INFRASTRUCTURE PARTNERS, LLC, By: Daniel R. Revers, President 2015-09-17 /s/ Daniel R. Revers, HIGH POINT INFRASTRUCTURE PARTNERS, LLC, LLC, By: Daniel R. Revers, President 2015-09-17 /s/ William B. Mathews, AMERICAN MIDSTREAM GP, LLC, By: William B. Mathews, Senior Vice President 2015-09-17 /s/ Daniel R. Revers, ARCLIGHT CAPITAL HOLDINGS, LLC, By: Daniel R. Revers, President 2015-09-17 /s/ Daniel R. Revers, ARCLIGHT CAPITAL PARTNERS, LLC, By: Daniel R. Revers, President 2015-09-17 /s/ Daniel R. Revers, ARCLIGHT ENERGY PARTNERS FUND V, L.P., LLC, By: ArcLight PEF GP V, LLC, its General Partner, By: ArcLight Capital Holdings, LLC, its Manager, By: Daniel R. Revers, Managing Partner 2015-09-17 /s/ Daniel R. Revers 2015-09-17