FORM10-Q PLAINS ALL AMERICAN PIPELINE, L.P. (Exact name of registrant as specified in its charter) 76-0582150(I.R.S. Employer Identification No.) (State or other jurisdiction of incorporation or organization) Indicate by check mark whether the registrant (1)has filed all reports required to be filed by Section13 or 15(d)of the SecuritiesExchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submittedpursuant to Rule405 of Regulation S-T during the preceding 12 months (or for such shorter period that the registrant was required to Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smallerreporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period forcomplying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act.☐ Indicate by check mark whether the registrant is a shell company (as defined in Rule12b-2 of the Exchange Act).☐Yes☑ As of May1, 2026, there were 705,531,683 Common Units outstanding. PLAINS ALL AMERICAN PIPELINE, L.P. AND SUBSIDIARIESTABLE OF CONTENTS PARTI. FINANCIAL INFORMATION Item1. UNAUDITED CONDENSED CONSOLIDATED FINANCIAL STATEMENTS:Condensed Consolidated Balance Sheets: As of March 31, 2026and December31, 2025Condensed Consolidated Statements of Operations: For the three months ended March 31, 2026 and2025Condensed Consolidated Statements of Comprehensive Income: For the three months ended March 31, 2026and2025Condensed Consolidated Statements of Changes in Accumulated Other Comprehensive Income/(Loss): For the threemonths ended March 31, 2026 and 2025Condensed Consolidated Statements of Cash Flows: For the three months ended March 31, 2026 and 2025Condensed Consolidated Statements of Changes in Partners’ Capital: For the three months ended March 31,2026and2025 Notes to the Condensed Consolidated Financial Statements: 1. Organization and Basis of Consolidation and Presentation2. Discontinued Operations3. Revenues and Accounts Receivable4. Net Income Per Common Unit5. Inventory, Linefill and Long-term Inventory6. Debt7. Partners’ Capital and Distributions8. Derivatives and Risk Management Activities9. Related Party Transactions10. Commitments and Contingencies11. Segment Information Item2. MANAGEMENT’S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTSOFOPERATIONS PARTII. OTHER INFORMATION Item1. LEGAL PROCEEDINGSItem1A. RISK FACTORSItem2. UNREGISTERED SALES OF EQUITY SECURITIES AND USE OF PROCEEDSItem3. DEFAULTS UPON SENIOR SECURITIESItem4. MINE SAFETY DISCLOSURESItem5. OTHER INFORMATIONItem6. EXHIBITS PARTI. FINANCIAL INFORMATION Item 1.UNAUDITED CONDENSED CONSOLIDATED FINANCIAL STATEMENTS PLAINS ALL AMERICAN PIPELINE,L.P. AND SUBSIDIARIESCONDENSED CONSOLIDATED BALANCE SHEETS Cash and cash equivalents$171$328Trade accounts receivable and other receivables, net4,8213,598 PLAINS ALL AMERICAN PIPELINE,L.P. AND SUBSIDIARIESCONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN Table of Contents PLAINS ALL AMERICAN PIPELINE,L.P. AND SUBSIDIARIESNOTES TO THE UNAUDITED CONDENSED CONSOLIDATED FINANCIAL STATEMENTS Note1—Organization and Basis of Consolidation and Presentation Organization Plains All American Pipeline, L.P. (“PAA”) is a publicly-traded Delaware limited partnership formed in 1998. Our operationsare conducted directly and indirectly through our primary operating subsidiaries. As used in this Form10-Q and unless the contextindicates otherwise, the terms “Partnership,” “we,” “us,” “our,” “ours” and similar terms refer to PAA and its subsidiaries. Our business model integrates large-scale supply aggregation capabilities with the ownership and operation of criticalmidstream infrastructure systems that connect major producing regions to key demand centers and export terminals. As one of thelargest crude oil midstream service providers in North America, we own an extensive network of pipeline transportation, terminalling,storage and gathering assets in key crude oil producing basins (including the Permian Basin) and transportation corridors and at major Our non-economic general partner interest is held by PAA GP LLC (“PAA GP”), a Delaware limited liability company, whosesole member is Plains AAP, L.P. (“AAP”), a Delaware limited partnership. In addition to its ownership of PAA GP, as of March31,2026, AAP also owned a limited partner interest in us through its ownership of approximately 233.0 million of our common units(approximately 31% of our total outstanding common units and Series A preferred units combined). Plains All American GP LLC (“GP