{"url_path":"/sec/paa/proxy/2026-05-13/000110465926060367","section_key":"body","section_title":"DEFA14A body","topic":"sec","document":{"doc_type":"DEFA14A","doc_date":"2026-05-13","source_url":"https://www.sec.gov/Archives/edgar/data/1070423/0001104659-26-060367-index.html","accession_number":"0001104659-26-060367","cik":"0001070423","ticker":"PAA","issuer_name":"PLAINS ALL AMERICAN PIPELINE LP","edgar_url":"https://www.sec.gov/Archives/edgar/data/1070423/0001104659-26-060367-index.html","primary_entity_key":"0001070423","primary_entity_name":"PLAINS ALL AMERICAN PIPELINE LP"},"word_count":977,"has_tables":true,"body_markdown":"DEFA14A\n1\ntm2614302d3_defa14a.htm\nDEFA14A\n\n**UNITED STATES**\n\n**SECURITIES AND EXCHANGE COMMISSION**\n\n**Washington, D.C. 20549**\n\n**SCHEDULE 14A**\n\nProxy Statement Pursuant to Section 14(a) of\n\nthe Securities Exchange Act of 1934 (Amendment\nNo.     )\n\nFiled by the Registrant x\n\nFiled\nby a Party other than the Registrant ¨\n\nCheck the appropriate box:\n\n¨\nPreliminary Proxy Statement\n\n¨\n**Confidential, for Use of the Commission Only (as permitted by Rule 14a-6(e)(2))**\n\n¨\nDefinitive Proxy Statement\n\nx\nDefinitive Additional Materials\n\n¨\nSoliciting Material under §240.14a-12\n\n**PLAINS ALL AMERICAN PIPELINE, L.P.**\n\n(Name of Registrant as Specified In Its Charter)\n\n(Name of Person(s) Filing Proxy Statement, if other than the Registrant)\n\nPayment of Filing Fee (Check the appropriate box):\n\nx\nNo fee required.\n\n¨\nFee paid previously with preliminary materials.\n\n¨\nFee computed on table in exhibit required by Item 25(b) per Exchange Act Rules 14a6(i)(1) and 0-11.\n\nMay 13, 2026\n\n**SUPPLEMENT TO PROXY STATEMENT FOR THE ANNUAL\nMEETING**\n\n**OF UNITHOLDERS TO BE HELD ON MAY 20, 2026**\n\nTo the Unitholders of Plains All American Pipeline, L.P.:\n\nThis proxy statement supplement dated May 13,\n2026 (this “Supplement”) supplements the definitive proxy statement on Schedule 14A of Plains All American Pipeline, L.P.\n(“PAA” or the “Company”) dated April 10, 2026 (as previously supplemented, the “Proxy Statement”)\nfor the Company’s Annual Meeting of Unitholders to be held on May 20, 2026.\n\n**THIS SUPPLEMENT SHOULD BE READ IN CONJUNCTION\nWITH THE PROXY STATEMENT. EXCEPT AS SPECIFICALLY SUPPLEMENTED BY THE INFORMATION CONTAINED HEREIN, THIS SUPPLEMENT DOES NOT MODIFY ANY\nOTHER INFORMATION SET FORTH IN THE PROXY STATEMENT.**\n\n**Appointment of Cynthia B. Taylor as a Director**\n\nOn May 11, 2026, the board of directors (the\n“Board”) of PAA GP Holdings LLC appointed Cynthia B. Taylor as an independent member of the Board serving in Class III.\nMs. Taylor will also serve as a member of the Compensation Committee and the Health, Safety, Environmental and Sustainability Committee.\nThe Board has responsibility for managing the business and affairs of PAA and of Plains GP Holdings, L.P. (“PAGP”).\n\nMs. Taylor has over 30 years of energy industry\nexperience, most recently serving as Chief Executive Officer and President of Oil States International, Inc. and as a member of the\nOil States Board of Directors. She held these positions from May 2007 until her retirement from Oil States in May 2026. From\nMay 2006 until May 2007, Ms. Taylor served as President and Chief Operating Officer of Oil States and served as Senior\nVice President—Chief Financial Officer and Treasurer prior to that. From August 1999 to May 2000, Ms. Taylor was\nthe Chief Financial Officer of L.E. Simmons & Associates, Incorporated. Ms. Taylor served as the Vice President—Controller\nof Cliffs Drilling Company from July 1992 to August 1999 and held various management positions with Ernst & Young\nLLP, a public accounting firm, from January 1984 to July 1992. Ms. Taylor was a director of the Federal Reserve Bank of\nDallas from January 2020 through December 31, 2025 and served as a director of the Federal Reserve Bank's Houston Branch\nfrom 2018 to 2019. She has also served as a director of AT&T Inc. since 2013 and serves as chair of the AT&T audit committee.\nShe received a B.B.A. in Accounting from Texas A&M University and is a Certified Public Accountant.\n\nThe Board believes that Ms. Taylor’s\npublic company executive leadership skills and her strategic, operational and financial background in the energy industry will bring a\nvaluable perspective to the Board.\n\nBased on a review of all relevant identified transactions\nor relationships between Ms. Taylor, or any of her family members, and the Company, its senior management and its independent auditors,\nthe Board has affirmatively determined that Ms. Taylor is an independent director pursuant to applicable Nasdaq and SEC rules. There\nare no family relationships between Ms. Taylor and any of the Company’s directors or executive officers.\n\n1\n\nConsistent with our compensation program for non-employee\ndirectors, Ms. Taylor will receive an annual cash retainer of $120,000 for service as a Board member. She will also receive an annual\ngrant of phantom Class A Shares of PAGP having a market value on the date of grant equal to approximately $160,000 (based on a volume\nweighted average price for the 10-trading day period beginning five days before and ending five days after the ex-dividend date immediately\npreceding the date of grant). These annual grants will vest (become payable in Class A Shares of PAGP) one year from the date of\ngrant and include associated distribution equivalent rights. Ms. Taylor’s initial compensation may be adjusted as appropriate\nto take into account the effective date on which her Board service commences.\n\nMs. Taylor does not beneficially own any common\nunits of the Company. There are no arrangements or understandings between Ms. Taylor and any other person pursuant to which she was\nselected as a director. In addition, there are no transactions in which Ms. Taylor has an interest that would require disclosure\nunder Item 404(a) of Regulation S-K.\n\n**Voting Matters**\n\nYou are not being asked to vote on or ratify the\nappointment of Ms. Taylor at the Annual Meeting. Ms. Taylor, as a Class III director, is not a nominee for election at\nthe Annual Meeting. **Accordingly, there is no change to Proposal 1, Election of Class I Directors, included in the Proxy Statement.**\n\nPlease note that any proxy card that you requested\nor that we elected to deliver has not changed and may still be used to vote your units in connection with the Annual Meeting. **If you\nhave already submitted your vote, you do not need to take any further action.** Information on how to vote your units and how to change\nyour vote or revoke your proxy is contained in the Proxy Statement. **Unitholders are urged to vote their units prior to the Annual\nMeeting by using one of the methods described in the proxy statement.**\n\n2"}