Westlake Chemical Partners LP 10-Q

Item 1. Financial Statements WESTLAKE CHEMICAL PARTNERS LP CONSOLIDATED BALANCE SHEETS (Unaudited) September 30, 2025 December 31, 2024 (in thousands of dollars, except unit amounts) ASSETS Current assets Cash and cash equivalents $ 37,936 $ 58,316 Receivable under the Investment Management Agreement—Westlake Corporation ("Westlake") 13,396 134,557 Accounts receivable, net—Westlake 59,665 31,975 Accounts receivable, net—third parties 16,141 11,576 Inventories 3,078 4,058 Prepaid expenses and other current assets 641 444 Total current assets 130,857 240,926 Property, plant and equipment, net 902,813 903,588 Goodwill 5,814 5,814 Deferred charges and other assets, net 232,129 137,628 Total assets $ 1,271,613 $ 1,287,956 LIABILITIES Current liabilities Accounts payable—Westlake $ 8,741 $ 20,744 Accounts payable—third parties 14,349 17,708 Accrued and other liabilities 32,036 16,920 Total current liabilities 55,126 55,372 Long-term debt payable to Westlake 399,674 399,674 Deferred income taxes 1,518 1,546 Other liabilities 1,984 2,050 Total liabilities 458,302 458,642 Commitments and contingencies (Note 12) EQUITY Common unitholders—publicly and privately held ( 21,123,649 and 21,116,326 units issued and outstanding at September 30, 2025 and December 31, 2024, respectively) 462,093 471,328 Common unitholder—Westlake ( 14,122,230 and 14,122,230 units issued and outstanding at September 30, 2025 and December 31, 2024, respectively) 41,091 47,373 General partner—Westlake ( 242,572 ) ( 242,572 ) Total Westlake Chemical Partners LP partners' capital 260,612 276,129 Noncontrolling interest in Westlake Chemical OpCo LP ("OpCo") 552,699 553,185 Total equity 813,311 829,314 Total liabilities and equity $ 1,271,613 $ 1,287,956 The accompanying notes are an integral part of the consolidated financial statements. 1 Table of Contents WESTLAKE CHEMICAL PARTNERS LP CONSOLIDATED STATEMENTS OF OPERATIONS (Unaudited) Three Months Ended September 30, Nine Months Ended September 30, 2025 2024 2025 2024 (in thousands of dollars, except unit amounts and per unit data) Revenue Net sales—Westlake $ 276,539 $ 215,799 $ 736,396 $ 690,535 Net co-products, ethylene and other sales—third parties 32,359 61,196 107,250 155,301 Total net sales 308,898 276,995 843,646 845,836 Cost of sales 209,475 160,052 592,610 525,481 Gross profit 99,423 116,943 251,036 320,355 Selling, general and administrative expenses 7,444 7,254 21,218 21,936 Income from operations 91,979 109,689 229,818 298,419 Other income (expense) Interest expense—Westlake ( 5,947 ) ( 6,698 ) ( 17,391 ) ( 19,930 ) Other income, net 224 1,325 2,245 3,916 Income before income taxes 86,256 104,316 214,672 282,405 Provision for income taxes 42 216 354 633 Net income 86,214 104,100 214,318 281,772 Less: Net income attributable to noncontrolling interest in OpCo 71,561 85,964 180,159 234,376 Net income attributable to Westlake Chemical Partners LP and limited partners' interest in net income $ 14,653 $ 18,136 $ 34,159 $ 47,396 Net income per limited partner unit attributable to Westlake Chemical Partners LP (basic and diluted) Common units $ 0.42 $ 0.51 $ 0.97 $ 1.35 Weighted average limited partner units outstanding (basic and diluted) Common units—publicly and privately held 21,120,704 21,112,943 21,117,801 21,108,731 Common units—Westlake 14,122,230 14,122,230 14,122,230 14,122,230 The accompanying notes are an integral part of the consolidated financial statements. 2 Table of Contents WESTLAKE CHEMICAL PARTNERS LP CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY (Unaudited) Partnership Common Unitholders — Publicly and Privately Held Common Unitholder — Westlake General Partner — Westlake Noncontrolling Interest in OpCo Total (in thousands of dollars) Balances at December 31, 2024 $ 471,328 $ 47,373 $ ( 242,572 ) $ 553,185 $ 829,314 Net income 2,965 1,983 — 37,361 42,309 Distribution to unitholders ( 9,954 ) ( 6,657 ) — — ( 16,611 ) Distribution to noncontrolling interest retained in OpCo by Westlake — — — ( 51,906 ) ( 51,906 ) Balances at March 31, 2025 $ 464,339 $ 42,699 $ ( 242,572 ) $ 538,640 $ 803,106 Net income 8,724 5,834 — 71,237 85,795 Distribution to unitholders ( 9,954 ) ( 6,657 ) — — ( 16,611 ) Distribution to noncontrolling interest retained in OpCo by Westlake — — — ( 41,125 ) ( 41,125 ) Balances at June 30, 2025 $ 463,109 $ 41,876 $ ( 242,572 ) $ 568,752 $ 831,165 Net income 8,781 5,872 — 71,561 86,214 Units issued for vested phantom units 161 — — — 161 Distribution to unitholders ( 9,958 ) ( 6,657 ) — — ( 16,615 ) Distribution to noncontrolling interest retained in OpCo by Westlake — — — ( 87,614 ) ( 87,614 ) Balances at September 30, 2025 $ 462,093 $ 41,091 $ ( 242,572 ) $ 552,699 $ 813,311 The accompanying notes are an integral part of the consolidated financial statements. 3 Table of Contents WESTLAKE CHEMICAL PARTNERS LP CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY (Unaudited) Partnership Common Unitholders— Publicly and Privately Held Common Unitholder— Westlake General Partner— Westlake Noncontrolling Interest in OpCo Total (in thousands of dollars) Balances at December 31, 2023 $ 473,513 $ 48,993 $ ( 242,572 ) $ 576,316 $ 856,250 Net income 8,887 5,946 — 74,813 89,646 Distribution to unitholders ( 9,950 ) ( 6,657 ) — — ( 16,607 ) Distribution to noncontrolling interest retained in OpCo by Westlake — — — ( 81,044 ) ( 81,044 ) Balances at March 31, 2024 $ 472,450 $ 48,282 $ ( 242,572 ) $ 570,085 $ 848,245 Net income 8,644 5,783 — 73,599 88,026 Units issued for vested phantom units 55 — — — 55 Distribution to unitholders ( 9,950 ) ( 6,657 ) — — ( 16,607 ) Distribution to noncontrolling interest retained in OpCo by Westlake — — — ( 84,872 ) ( 84,872 ) Balances at June 30, 2024 $ 471,199 $ 47,408 $ ( 242,572 ) $ 558,812 $ 834,847 Net income 10,867 7,269 — 85,964 104,100 Units issued for vested phantom units 183 — — — 183 Distribution to unitholders ( 9,953 ) ( 6,657 ) — — ( 16,610 ) Distribution to noncontrolling interest retained in OpCo by Westlake — — — ( 84,706 ) ( 84,706 ) Balances at September 30, 2024 $ 472,296 $ 48,020 $ ( 242,572 ) $ 560,070 $ 837,814 The accompanying notes are an integral part of the consolidated financial statements. 4 Table of Contents WESTLAKE CHEMICAL PARTNERS LP CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) Nine Months Ended September 30, 2025 2024 (in thousands of dollars) Cash flows from operating activities Net income $ 214,318 $ 281,772 Adjustments to reconcile net income to net cash provided by operating activities Depreciation and amortization 93,424 84,421 Loss from disposition of property, plant and equipment 2,279 2,241 Other losses (gains), net 92 ( 14 ) Changes in operating assets and liabilities Accounts receivable—third parties ( 4,685 ) ( 3,859 ) Net accounts receivable—Westlake ( 38,532 ) 6,933 Inventories 980 681 Prepaid expenses and other current assets ( 197 ) ( 225 ) Accounts payable—third parties ( 508 ) ( 373 ) Accrued and other liabilities 16,736 ( 1,927 ) Deferred charges and other assets and others, net ( 123,817 ) ( 17,118 ) Net cash provided by operating activities 160,090 352,532 Cash flows from investing activities Additions to property, plant and equipment ( 69,988 ) ( 35,497 ) Investments with Westlake under the Investment Management Agreement — ( 15,000 ) Maturities of investments with Westlake under the Investment Management Agreement 120,000 — Net cash provided by (used for) investing activities 50,012 ( 50,497 ) Cash flows from financing activities Proceeds from debt payable to Westlake 135,000 163,000 Repayment of debt payable to Westlake ( 135,000 ) ( 163,000 ) Distributions to noncontrolling interest retained in OpCo by Westlake ( 180,645 ) ( 250,622 ) Distributions to unitholders ( 49,837 ) ( 49,824 ) Net cash used for financing activities ( 230,482 ) ( 300,446 ) Net increase (decrease) in cash and cash equivalents ( 20,380 ) 1,589 Cash and cash equivalents at beginning of period 58,316 58,619 Cash and cash equivalents at end of period $ 37,936 $ 60,208 The accompanying notes are an integral part of the consolidated financial statements. 5 Table of Contents WESTLAKE CHEMICAL PARTNERS LP NOTES TO CONSOLIDATED FINANCIAL STATEMENTS — Continued (Unaudited) (in thousands of dollars, except unit amounts and per unit data) 1. Description of Business and Basis of Presentation Description of Business Westlake Chemical Partners LP (the "Partnership") is a Delaware limited partnership formed in March 2014 to operate, acquire and develop ethylene production facilities and related assets. On August 4, 2014, the Partnership completed its initial public offering (the "IPO") of 12,937,500 common units representing limited partner interests. In connection with the IPO, the Partnership acquired a 10.6 % limited partner interest in Westlake Chemical OpCo LP ("OpCo") and a 100 % interest in Westlake Chemical OpCo GP LLC ("OpCo GP"), which is the general partner of OpCo. OpCo owns three ethylene production facilities and one common carrier ethylene pipeline (collectively, the "Contributed Assets"). Since the IPO, the Partnership has periodically purchased additional limited partner interest in OpCo. Most recently, on March 29, 2019, the Partnership purchased an additional 4.5 % newly-issued limited partner interest in OpCo for approximately $ 201,445 , resulting in an aggregate 22.8 % limited partner interest in OpCo, effective January 1, 2019. The remaining 77.2 % limited partner interest in OpCo is owned by Westlake Corporation. Basis of Presentation The accompanying unaudited consolidated interim financial statements were prepared in accordance with the rules and regulations of the Securities and Exchange Commission (the "SEC") for interim periods. Accordingly, certain information and footnotes required for complete financial statements under generally accepted accounting principles in the United States ("U.S. GAAP") have not been included. These interim consolidated financial statements should be read in conjunction with the consolidated financial statements and notes thereto of the Partnership included in the annual report on Form 10-K for the fiscal year ended December 31, 2024 (the "2024 Form 10-K"), filed with the SEC on March 5, 2025. These financial statements have been prepared in conformity with the accounting principles and practices as disclosed in the notes to the consolidated financial statements of the Partnership for the fiscal year ended December 31, 2024. References to "Westlake" refer collectively to Westlake Corporation and its subsidiaries, other than the Partnership, OpCo and OpCo GP. The Partnership holds a 22.8 % limited partner interest and the entire non-economic general partner interest in OpCo. The remaining 77.2 % limited partner interest in OpCo is owned directly by Westlake, which has no rights to direct the activities that most significantly impact the economic performance of OpCo. As a result of the fact that substantially all of OpCo's activities are conducted on behalf of Westlake, and the fact that OpCo exhibits disproportionality of voting rights to economic interest, OpCo was deemed to be a variable interest entity. The Partnership, through its ownership of OpCo's general partner, has the power to direct the activities that most significantly impact the economic performance of OpCo, and it also has the obligation or right to absorb losses or receive benefits from OpCo that could potentially be significant to OpCo. As such, the Partnership was determined to be OpCo's primary beneficiary and therefore consolidates OpCo's results of operations and financial position. The Partnership's operations consist exclusively of the variable interest entity's operations and, as such, no additional variable interest entity disclosures are considered necessary. Westlake's retained interest of 77.2 % is recorded as noncontrolling interest in the Partnership's consolidated financial statements. In the opinion of the Partnership's management, the accompanying unaudited consolidated interim financial statements reflect all adjustments (consisting only of normal recurring adjustments) that are necessary for a fair statement of the Partnership's financial position as of September 30, 2025, its results of operations for the three and nine months ended September 30, 2025 and 2024 and the changes in its cash position for the nine months ended September 30, 2025 and 2024. Results of operations and changes in cash position for the interim periods presented are not necessarily indicative of the results that will be realized for the fiscal year ending December 31, 2025 or any other interim period. The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues and expenses and the disclosure of contingent assets and liabilities. Actual results could differ materially from those estimates. 6 Table of Contents WESTLAKE CHEMICAL PARTNERS LP NOTES TO CONSOLIDATED FINANCIAL STATEMENTS — Continued (Unaudited) (in thousands of dollars, except unit amounts and per unit data) Recently Issued Accounting Pronouncements Measurement of Credit Losses for Accounts Receivable and Contract Assets (ASU No. 2025-05) In July 2025, the Financial Accounting Standards Board ("FASB") issued an accounting standards update to add a practical expedient in developing reasonable and supportable forecasts as part of estimating expected credit losses. All entities may elect a practical expedient that assumes the current conditions as of the balance sheet date do not change for the remaining life of the asset. The amendments in this update are effective for annual reporting periods beginning after December 15, 2025 and interim reporting periods within those annual reporting periods, with early adoption permitted. Entities should apply the new guidance prospectively. The Partnership does not expect that this accounting standard, upon adoption, will have a material impact on the Partnership's consolidated financial statements. Disaggregation of Income Statement Expenses (ASU No. 2024-03) In November 2024, the FASB issued an accounting standards update requiring public entities to disclose, on an annual and interim basis, detailed information about the types of expenses in relevant expense captions presented on the face of the income statement, including amounts for inventory purchases, employee compensation, depreciation and amortization of intangible assets and a qualitative description for remaining amounts not separately disaggregated. Additionally, the update requires disclosure of total selling expenses, and in annual periods, an entity's definition of selling expenses. The amendments in this update are effective for annual reporting periods beginning after December 15, 2026, and interim periods beginning after December 15, 2027 and are to be applied either prospectively or retrospectively. Early adoption is permitted. The Partnership is currently evaluating the impact of the update on the disclosures in the Partnership's consolidated financial statements. Income Taxes (ASU No. 2023-09) In December 2023, the FASB issued an accounting standards update requiring additional tax disclosures primarily related to the rate reconciliation and income taxes paid disclosures. The amendments in this update will be effective for annual periods beginning after December 15, 2024 and are to be applied on a prospective basis. Retrospective application is also permitted. The update is not expected to have a material impact on the disclosures in the Partnership's consolidated financial statements. Recently Adopted Accounting Pronouncement Segment Reporting (ASU No. 2023-07) In November 2023, the FASB issued an accounting standards update requiring public entities to disclose on an annual and interim basis, significant segment expenses that are regularly provided to the chief operating decision maker ("CODM") and on an annual basis, the title and position of the CODM and an explanation of how the CODM uses the reported measure(s) of segment profit or loss in assessing segment performance and deciding how to allocate resources. The update also requires that a public entity that has a single reportable segment provide all disclosures required by the update as well as all existing segment disclosures in Topic 280. The amendments in this update are effective for fiscal years beginning after December 15, 2023, and interim periods within fiscal years beginning after December 15, 2024 and are to be applied retrospectively to all prior periods presented in the financial statements. Early adoption is permitted. The Partnership adopted this accounting standard effective for the annual 2024 financial statements and interim period financial statements thereafter, and the adoption resulted in additional segment disclosures (see Note 13). 2. Accounts Receivable—Third Parties Accounts receivable—third parties consist of the following: September 30, 2025 December 31, 2024 Trade customers $ 16,442 $ 11,757 Allowance for credit losses ( 301 ) ( 181 ) Accounts receivable, net—third parties $ 16,141 $ 11,576 7 Table of Contents WESTLAKE CHEMICAL PARTNERS LP NOTES TO CONSOLIDATED FINANCIAL STATEMENTS — Continued (Unaudited) (in thousands of dollars, except unit amounts and per unit data) 3. Inventories Inventories consist of the following: September 30, 2025 December 31, 2024 Finished products $ 2,609 $ 3,748 Feedstock, additives and chemicals 469 310 Inventories $ 3,078 $ 4,058 4. Property, Plant and Equipment Depreciation expense on property, plant and equipment of $ 21,966 and $ 21,626 is included in cost of sales in the consolidated statements of operations for the three months ended September 30, 2025 and 2024, respectively. Depreciation expense on property, plant and equipment of $ 64,389 and $ 64,993 is included in cost of sales in the consolidated statements of operations for the nine months ended September 30, 2025 and 2024 , respectively. 5. Deferred Charges and Other Assets Amortization expense on deferred charges and other assets of $ 11,906 and $ 6,486 is included in cost of sales in the consolidated statements of operations for the three months ended September 30, 2025 and 2024, respectively . Amortization expense on deferred charges and other assets of $ 29,035 and $ 19,428 is included in cost of sales in the consolidated statements of operations for the nine months ended September 30, 2025 and 2024, respectively. 6. Distributions and Net Income Per Limited Partner Unit On October 28, 2025, the board of directors of Westlake Chemical Partners GP LLC ("Westlake GP"), the Partnership's general partner, declared a quarterly cash distribution for the three months ended September 30, 2025 of 0.4714 per common unit. This distribution is payable on November 26, 2025 to unitholders of record as of November 10, 2025. Distributions are declared subsequent to quarter end; therefore, the table below represents total cash distributions declared from earnings of the related periods pertaining to such distributions. Three Months Ended September 30, Nine Months Ended September 30, 2025 2024 2025 2024 Net income attributable to the Partnership $ 14,653 $ 18,136 $ 34,159 $ 47,396 Less: Limited partners' distribution declared on common units 16,615 16,611 49,838 49,826 Net income in excess of distribution (Distribution in excess of net income) $ ( 1,962 ) $ 1,525 $ ( 15,679 ) $ ( 2,430 ) Net income per unit applicable to common limited partner units is computed by dividing the respective limited partners' interest in net income by the weighted-average number of common units outstanding for the period. Because the Partnership has more than one class of participating securities, it uses the two-class method when calculating the net income per unit applicable to limited partners. The classes of participating securities include common units and incentive distribution rights. Net income attributable to the Partnership is allocated to the unitholders in accordance with their respective ownership percentages in preparation of the consolidated statements of changes in equity. However, when distributions related to the incentive distribution rights are made, net income equal to the amount of those distributions is first allocated to the general partner before the remaining net income is allocated to the unitholders based on their respective ownership percentages. Basic and diluted net income per unit is the same because the Partnership does not have any potentially dilutive units outstanding for the periods presented. 8 Table of Contents WESTLAKE CHEMICAL PARTNERS LP NOTES TO CONSOLIDATED FINANCIAL STATEMENTS — Continued (Unaudited) (in thousands of dollars, except unit amounts and per unit data) Three Months Ended September 30, 2025 Limited Partners' Common Units Incentive Distribution Rights Total Net income attributable to the Partnership: Distribution $ 16,615 $ — $ 16,615 Distribution in excess of net income ( 1,962 ) — ( 1,962 ) Net income $ 14,653 $ — $ 14,653 Weighted average units outstanding: Basic and diluted 35,242,934 35,242,934 Net income per limited partner unit: Basic and diluted $ 0.42 Three Months Ended September 30, 2024 Limited Partners' Common Units Incentive Distribution Rights Total Net income attributable to the Partnership: Distribution $ 16,611 $ — $ 16,611 Net income in excess of distribution 1,525 — 1,525 Net income $ 18,136 $ — $ 18,136 Weighted average units outstanding: Basic and diluted 35,235,173 35,235,173 Net income per limited partner unit: Basic and diluted $ 0.51 Nine Months Ended September 30, 2025 Limited Partners' Common Units Incentive Distribution Rights Total Net income attributable to the Partnership: Distribution $ 49,838 $ — $ 49,838 Distribution in excess of net income ( 15,679 ) — ( 15,679 ) Net income $ 34,159 $ — $ 34,159 Weighted average units outstanding: Basic and diluted 35,240,031 35,240,031 Net income per limited partner unit: Basic and diluted $ 0.97 9 Table of Contents WESTLAKE CHEMICAL PARTNERS LP NOTES TO CONSOLIDATED FINANCIAL STATEMENTS — Continued (Unaudited) (in thousands of dollars, except unit amounts and per unit data) Nine Months Ended September 30, 2024 Limited Partners' Common Units Incentive Distribution Rights Total Net income attributable to the Partnership: Distribution $ 49,826 $ — $ 49,826 Distribution in excess of net income ( 2,430 ) — ( 2,430 ) Net income $ 47,396 $ — $ 47,396 Weighted average units outstanding: Basic and diluted 35,230,961 35,230,961 Net income per limited partner unit: Basic and diluted $ 1.35 The amended Partnership Agreement provides that the Partnership will distribute cash that is deemed to be an appropriate portion of the Partnership's total operating surplus. If cash distributions to the Partnership's unitholders exceed $ 1.2938 per common unit in any quarter, the Partnership's unitholders and Westlake, as the holder of the Partnership's incentive distribution rights, will receive distributions according to the following percentage allocations: Marginal Percentage Interest in Distributions Total Quarterly Distribution Per Unit Unitholders IDR Holders Above $ 1.2938 up to $ 1.4063 85.0 % 15.0 % Above $ 1.4063 up to $ 1.6875 75.0 % 25.0 % Above $ 1.6875 50.0 % 50.0 % The Partnership's distribution for the three months ended September 30, 2025 did not exceed the $ 1.2938 per unit threshold, and, as a result, no distribution was made with respect to the Partnership's incentive distribution rights to Westlake, as the holder of the Partnership's incentive distribution rights. Distributions Per Common Unit Distributions per common unit for the three and nine months ended September 30, 2025 and 2024 were as follows: Three Months Ended September 30, Nine Months Ended September 30, 2025 2024 2025 2024 Distributions per common unit $ 0.4714 $ 0.4714 $ 1.4142 $ 1.4142 7. Partners' Equity On October 4, 2018, the Partnership and Westlake Chemical Partners GP LLC, the general partner of the Partnership, entered into an Equity Distribution Agreement with UBS Securities LLC, Barclays Capital Inc., Citigroup Global Markets Inc., Deutsche Bank Securities Inc., RBC Capital Markets, LLC, Merrill Lynch, Pierce, Fenner & Smith Incorporated and Wells Fargo Securities, LLC to offer and sell the Partnership's common units, from time to time, up to an aggregate offering amount of $ 50,000 . The Equity Distribution Agreement was amended on February 28, 2020 to reference a new shelf registration and subsequent renewals thereof for utilization under this agreement. No common units were issued under this program as of September 30, 2025. On March 29, 2019, the Partnership completed the issuance and sale of 2,940,818 common units at a price of $ 21.40 per unit through a private placement. TTWF LP, Westlake's principal stockholder and a related party, acquired 1,401,869 common units out of 2,940,818 common units issued in the private placement. 10 Table of Contents WESTLAKE CHEMICAL PARTNERS LP NOTES TO CONSOLIDATED FINANCIAL STATEMENTS — Continued (Unaudited) (in thousands of dollars, except unit amounts and per unit data) 8. Related Party Transactions Related party transactions between the Partnership, OpCo and Westlake are primarily based on agreements such as the Ethylene Sales Agreement, the Feedstock Supply Agreement, the Services and Secondment Agreement, Site Lease Agreements, the Omnibus Agreement, the Investment Management Agreement, the Exchange Agreement, the OpCo Partnership Agreement, the OpCo Revolver and the MLP Revolver. These agreements, discussed in detail in the Partnership's 2024 consolidated financial statements included in the 2024 Form 10-K filed on March 5, 2025, reflect the pervasive effect of the relationship with Westlake on the Partnership's operations and its consolidated financial statements. Pursuant to these agreements, the Partnership and OpCo regularly enter into transactions with Westlake. See below for descriptions and details of significant related party transactions. Sales to Related Parties OpCo sells ethylene to Westlake under the Ethylene Sales Agreement. Additionally, the Partnership and OpCo from time to time provide other services or products for which it charges Westlake a fee. OpCo sells a significant portion of its ethylene production to Westlake. Sales to related parties were as follows: Three Months Ended September 30, Nine Months Ended September 30, 2025 2024 2025 2024 Net sales—Westlake $ 276,539 $ 215,799 $ 736,396 $ 690,535 As of September 30, 2025, OpCo forecasted an annual production deficiency under the Ethylene Sales Agreement for the full year 2025 primarily due to the Petro 1 turnaround extending into April 2025, which was later than the planned completion in March 2025. As a result, the Partnership recognized buyer deficiency fees of $ 13,613 in the second quarter of 2025. The total buyer deficiency fees recognized by the Partnership during the nine months ended September 30, 2025 was $ 13,613 . The buyer deficiency fee is measured based upon the lower of the actual production deficiency at period end or the estimated annual production deficiency. The buyer deficiency fees are classified as a component of net sales—Westlake. Cost of Sales from Related Parties Charges for goods and services purchased by the Partnership and OpCo from Westlake and included in cost of sales relate primarily to feedstock purchased under the Feedstock Supply Agreement and services provided under the Services and Secondment Agreement. A significant portion of the Partnership's inputs included in cost of sales are supplied by Westlake. Charges from related parties for significant inputs included in cost of sales were as follows: Three Months Ended September 30, Nine Months Ended September 30, 2025 2024 2025 2024 Feedstock purchased from Westlake and included in cost of sales $ 95,110 $ 65,053 $ 271,176 $ 220,597 Other charges from Westlake and included in cost of sales 33,952 31,274 99,158 92,940 Services from Related Parties Included in Selling, General and Administrative Expenses Charges for services purchased by the Partnership from Westlake and included in selling, general and administrative expenses primarily relate to services Westlake performs on behalf of the Partnership under the Omnibus Agreement, including the Partnership's finance, legal, information technology, human resources, communication, ethics and compliance and other administrative functions. Charges from related parties included within selling, general and administrative expenses were as follows: Three Months Ended September 30, Nine Months Ended September 30, 2025 2024 2025 2024 Services received from Westlake and included in selling, general and administrative expenses $ 6,691 $ 6,618 $ 18,398 $ 19,793 11 Table of Contents WESTLAKE CHEMICAL PARTNERS LP NOTES TO CONSOLIDATED FINANCIAL STATEMENTS — Continued (Unaudited) (in thousands of dollars, except unit amounts and per unit data) Goods and Services from Related Parties Capitalized as Assets Charges for goods and services purchased by the Partnership and OpCo from Westlake, which were capitalized as assets, relate primarily to the services of Westlake employees under the Services and Secondment Agreement. Charges from related parties for goods and services capitalized as assets were as follows: Three Months Ended September 30, Nine Months Ended September 30, 2025 2024 2025 2024 Goods and services purchased from Westlake and capitalized as assets $ 462 $ 795 $ 6,943 $ 1,644 Receivable under the Investment Management Agreement On August 1, 2017, the Partnership, OpCo and Westlake executed an investment management agreement (the "Investment Management Agreement") that authorized Westlake to invest the Partnership's and OpCo's excess cash with Westlake for durations of up to a maximum of nine months. Per the terms of the Investment Management Agreement, the Partnership earns a market return plus five basis points and Westlake provides daily availability of the invested cash to meet any liquidity needs of the Partnership or OpCo. Accrued interest of $ 224 and $ 1,385 was included in the receivable under the Investment Management Agreement balance at September 30, 2025 and December 31, 2024, respectively. Total interest earned related to the Investment Management Agreement was $ 224 and $ 1,368 for the three months ended September 30, 2025 and 2024, respectively, and $ 2,333 and $ 3,979 for the nine months ended September 30, 2025 and 2024, respectively. The Partnership's receivable under the Investment Management Agreement was as follows: September 30, 2025 December 31, 2024 Receivable under the Investment Management Agreement $ 13,396 $ 134,557 Accounts Receivable from Related Parties The Partnership's accounts receivable from Westlake result primarily from ethylene sales to Westlake and any buyer deficiency fee and shortfall fee recognized under the Ethylene Sales Agreement. The buyer deficiency fees discussed above under "Sales to Related Parties" recognized in the nine months ended September 30, 2025 are scheduled to be received by the Partnership after December 31, 2025. As a result of the Partnership's decision to postpone the maintenance turnaround at the Petro 1 facility from the third quarter of 2024 to the first quarter of 2025, OpCo's production resulted in "excess quantities" of ethylene for the contract year ended December 31, 2024. Pursuant to the terms of the Ethylene Sales Agreement, the excess quantities produced were sold to Westlake at prices that excluded certain non-variable costs of production. As of December 31, 2024, accounts receivable included sales associated with the excess quantities, which were at a lower sales price. 12 Table of Contents WESTLAKE CHEMICAL PARTNERS LP NOTES TO CONSOLIDATED FINANCIAL STATEMENTS — Continued (Unaudited) (in thousands of dollars, except unit amounts and per unit data) The Partnership's accounts receivable from Westlake were as follows: September 30, 2025 December 31, 2024 Accounts receivable—Westlake $ 59,665 $ 31,975 Accounts Payable to Related Parties The Partnership's accounts payable to Westlake result primarily from feedstock purchases under the Feedstock Supply Agreement and services provided under the Services and Secondment Agreement and the Omnibus Agreement. The Partnership's accounts payable to Westlake were as follows: September 30, 2025 December 31, 2024 Accounts payable—Westlake $ 8,741 $ 20,744 Related Party Leases OpCo is obligated to Westlake under various long-term and short-term noncancelable operating leases, primarily related to rail cars and land. Operating lease rentals paid to Westlake for such leases were $ 468 and $ 471 for the three months ended September 30, 2025 and 2024, respectively, and $ 1,246 and $ 1,326 for the nine months ended September 30, 2025 and 2024 respectively, an d are reflected in other charges from Westlake that are included in cost of sales. OpCo has two site lease agreements with Westlake, each of which has a term of 50 years. Pursuant to the site lease agreements, OpCo pays Westlake one dollar per site per year. Debt Payable to Related Parties See Note 9 for a description of related party debt payable balances. Interest on related party debt payable balances, net of capitalized interest, for the three months ended September 30, 2025 and 2024 was $ 5,947 and $ 6,698 , respecti vely. Interest on related party debt payable balances, net of capitalized interest, for the nine months ended September 30, 2025 and 2024 was $ 17,391 and $ 19,930 , respectively. Interest on related party debt payable is presented as interest expense—Westlake in the consolidated statements of operations. At September 30, 2025 and December 31, 2024, accrued interest on related party debt was $ 5,945 and $ 5,848 , respectively, and is reflected as a component of accrued and other liabilities in the consolidated balance sheets. Debt payable to related parties was as follows: September 30, 2025 December 31, 2024 Long-term debt payable to Westlake $ 399,674 $ 399,674 Major Customer and Concentration of Credit Risk During the three months ended September 30, 2025 and 2024, Westlake accounted for approximately 89.5 % and 77.9 %, respectively, of the Partnership's net sale s. During the nine months ended September 30, 2025 and 2024, Westlake accounted for approximately 87.3 % and 81.6 % , respectively, of the Partnership's net sales. 13 Table of Contents WESTLAKE CHEMICAL PARTNERS LP NOTES TO CONSOLIDATED FINANCIAL STATEMENTS — Continued (Unaudited) (in thousands of dollars, except unit amounts and per unit data) 9. Long-Term Debt Payable to Westlake Long-term debt payable to Westlake consists of the following: September 30, 2025 December 31, 2024 OpCo Revolver $ 22,619 $ 22,619 MLP Revolver 377,055 377,055 Long-term debt payable to Westlake $ 399,674 $ 399,674 As of September 30, 2025, outstanding borrowings under the OpCo Revolver and the MLP Revolver bore interest at the Secured Overnight Financing Rate, as administered by the Federal Reserve Bank of New York ("SOFR") plus the Applicable Margin plus a 0.10 % credit spread adjustment. The Applicable Margin under the OpCo Revolver is 1.75 %. The Applicable Margin under the MLP Revolver varies between 1.75 % and 2.75 %, depending on the Partnership's Consolidated Leverage Ratio. The OpCo Revolver and the MLP Revolver are scheduled to mature on July 12, 2027. The weighted average interest rate on all long-term debt was 6.1 % and 6.4 % at September 30, 2025 and December 31, 2024, respectively. As of September 30, 2025, the Partnership was in compliance with all of the covenants under the OpCo Revolver and the MLP Revolver. 10. Fair Value Measurements The Partnership reports certain assets and liabilities at fair value, which is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date (exit price). Under the accounting guidance for fair value measurements, inputs used to measure fair value are classified in one of three levels: Level 1: Quoted market prices in active markets for identical assets or liabilities. Level 2: Observable market-based inputs or unobservable inputs that are corroborated by market data. Level 3: Unobservable inputs that are not corroborated by market data. The Partnership has financial assets and liabilities subject to fair value measures. These financial assets and liabilities include cash and cash equivalents, accounts receivable, net, accounts payable and long-term debt payable to Westlake, all of which are recorded at carrying value. The amounts reported in the consolidated balance sheets for cash and cash equivalents, accounts receivable, net and accounts payable approximate their fair value due to the short maturities of these instruments. The carrying and fair values of the Partnership's long-term debt at September 30, 2025 and December 31, 2024 are summarized in the table below. The fair value of long-term debt is determined based on the present value of expected future cash flows using a discounted cash flow methodology. Because the Partnership's valuation methodology used for long-term debt requires the use of significant unobservable inputs, the inputs used to measure the fair value of the Partnership's long-term debt are classified as Level 3 within the fair value hierarchy. Inputs used to estimate the fair values of the Partnership's long-term debt include the selection of an appropriate discount rate. September 30, 2025 December 31, 2024 Carrying Value Fair Value Carrying Value Fair Value Long-term debt payable to Westlake $ 399,674 $ 409,299 $ 399,674 $ 411,489 14 Table of Contents WESTLAKE CHEMICAL PARTNERS LP NOTES TO CONSOLIDATED FINANCIAL STATEMENTS — Continued (Unaudited) (in thousands of dollars, except unit amounts and per unit data) 11. Supplemental Information Accrued and Other Liabilities Accrued and other liabilities were $ 32,036 and $ 16,920 at September 30, 2025 and December 31, 2024, respectively. Accrued taxes, accrued turnaround costs and accrued interest on related party debt, which are components of accrued and other liabilities, were $ 6,177 , $ 12,649 and $ 5,945 , respectively, at September 30, 2025 and $ 2,415 , $ 933 and $ 5,848 , respectively, at December 31, 2024. No other component of accrued and other liabilities was more than five percent of total current liabilities. Cash Flow Information Non-cash Investing Activity Capital expenditure related liabilities, included in accounts payable—third parties and accrued and other liabilities, were $ 5,768 and $ 7,376 at September 30, 2025 and 2024, respectively. Interest Paid Interest paid by the Partnership, net of interest capitalized, was $ 17,292 and $ 19,852 for the nine months ended September 30, 2025 and 2024, respectively. Operating Leases Right-of-use assets obtained in exchange for operating lease obligations were $ 920 and $ 758 for the nine months ended September 30, 2025 and 2024, respectively. 12. Commitments and Contingencies The Partnership is subject to environmental laws and regulations that can impose civil and criminal sanctions and that may require the Partnership to mitigate the effects of contamination caused by the release or disposal of hazardous substances into the environment. These laws include the federal Clean Air Act, the federal Water Pollution Control Act, the Resource Conservation and Recovery Act, the Comprehensive Environmental Response, Compensation, and Liability Act ("CERCLA"), the Toxic Substances Control Act and various other federal, state and local laws and regulations. Under CERCLA, an owner or operator of property may be held strictly liable for remediating contamination without regard to whether that person caused the contamination, and without regard to whether the practices that resulted in the contamination were legal at the time they occurred. Because the Partnership's production sites have a history of industrial use, it is impossible to predict precisely what effect these legal requirements will have on the Partnership. Pursuant to the Omnibus Agreement, certain subsidiaries of Westlake will indemnify the Partnership for certain environmental and other liabilities that occurred or existed prior to August 4, 2014. Pursuant to the Services and Secondment Agreement, certain subsidiaries of Westlake will indemnify the Partnership for certain liabilities incurred in connection with the performance of Westlake's services under such agreement. The Partnership is also involved in other legal proceedings incidental to the conduct of its business. After considering all relevant facts and circumstances, including applicable insurance and indemnification by Westlake, the Partnership does not believe that any of these legal proceedings will have a material adverse effect on its financial condition, results of operations or cash flows. 15 Table of Contents WESTLAKE CHEMICAL PARTNERS LP NOTES TO CONSOLIDATED FINANCIAL STATEMENTS — Continued (Unaudited) (in thousands of dollars, except unit amounts and per unit data) 13. Segment Information The Partnership has one operating segment, which is the Partnership's reportable segment, OpCo. Consolidated net sales and provision for income taxes as disclosed in the consolidated statements of operations and depreciation and amortization and additions to property, plant and equipment as disclosed in the consolidated statements of cash flows are fully attributed to the OpCo segment, and as such, separate OpCo segment amounts are not repeated in the tables below. Three Months Ended September 30, Nine Months Ended September 30, 2025 2024 2025 2024 Significant segment expenses and other segment items OpCo Raw material, energy, manufacturing and logistics costs $ 175,603 $ 131,940 $ 499,186 $ 441,060 Depreciation and amortization 33,872 28,112 93,424 84,421 Total cost of sales 209,475 160,052 592,610 525,481 Selling, general and administrative expenses 6,579 6,372 18,653 19,018 Other segment items (1) 175 ( 749 ) ( 913 ) ( 2,168 ) Interest expense—Westlake OpCo $ 357 $ 360 $ 978 $ 1,115 Corporate 5,590 6,338 16,413 18,815 $ 5,947 $ 6,698 $ 17,391 $ 19,930 Net income OpCo $ 92,669 $ 111,320 $ 233,296 $ 303,505 A reconciliation of total segment net income to consolidated net income is as follows: Three Months Ended September 30, Nine Months Ended September 30, 2025 2024 2025 2024 Net income from OpCo $ 92,669 $ 111,320 $ 233,296 $ 303,505 Corporate net loss ( 6,455 ) ( 7,220 ) ( 18,978 ) ( 21,733 ) Net income $ 86,214 $ 104,100 $ 214,318 $ 281,772 September 30, 2025 December 31, 2024 Total assets OpCo $ 1,237,368 $ 1,238,420 Corporate 34,245 49,536 $ 1,271,613 $ 1,287,956 _____________________________ (1) Other segment items includes interest expense—Westlake, other income, net and provision for income taxes. 16 Table of Contents WESTLAKE CHEMICAL PARTNERS LP NOTES TO CONSOLIDATED FINANCIAL STATEMENTS — Continued (Unaudited) (in thousands of dollars, except unit amounts and per unit data) 14. Subsequent Events On October 28, 2025, OpCo and Westlake agreed to renew both the Ethylene Sales Agreement and the Feedstock Supply Agreement through December 31, 2027 in accordance with their respective terms (the "Renewal"), which each provide for an initial term through December 31, 2026 and automatic 12 -month renewal periods until terminated at the end of the initial term or any renewal term on not less than 12 -months' notice. In connection with the Renewal, on October 28, 2025, OpCo and certain affiliates of Westlake entered into an amendment to the Services and Secondment Agreement to align the date of expiration of such agreement with the date of expiration term of the Ethylene Sales Agreement. In addition, the Partnership, OpCo and certain affiliates of Westlake also entered into an amendment to the Omnibus Agreement to provide that the Omnibus Agreement would terminate upon termination of the Ethylene Sales Agreement. The amendment also addressed certain procedural requirements in connection with Westlake's obligation to indemnify the Partnership for certain matters, including, among others, environmental and tax matters, under the Omnibus Agreement. 17 Table of Contents