WLKP 10-K & 10-Q changes, risk factors and insider trading

•If OpCo is unable to renew or extend the Ethylene Sales Agreement beyond the initial 12-year term or the other agreements with Westlake upon expiration of these agreements, our ability to make distributions in the future could be materially adversely affected and the value of our units could decline.

•CostWe reimbursementsare dueobligated to reimburse our general partner and Westlake for services provided to us or on our behalfbehalf, which may reduce our earnings and therefore our cash available for distribution to our unitholders. The amount and timing of such reimbursements are determined by our general partner.

Westlake may be unable to generate enough cash flow from operations to meet its minimum obligations under the Ethylene Sales Agreement if its business is adversely impacted by competition, operational problems, international trade barriers, general adverse economic conditions or the inability to obtain feedstock. For example, lower prices of crude oil could lead to a reduction in the cost advantage for natural gas liquids-based ethylene derivatives in North America, such as Westlake's, as compared to naphtha-based ethylene derivatives. Additionally, Westlake operates internationally and could be adversely affected by trade barriers, tariffs and duties, or violations of international fair trade laws by global competitors. As a result, Westlake's margins and cash flows could be negatively impacted during such period. If Westlake is not able to meet its minimum payment obligations to OpCo as a result of any one or more of these factors, our ability to make distributions to our unitholders would be reduced or eliminated. The amount paid by Westlake will depend upon its ability to satisfy its minimum obligations under the Ethylene Sales Agreement and its ability and election to increase volumes above the minimums specified in the Ethylene Sales Agreement, which in turn are dependent upon, among other things, the level of polyethylene and polyvinyl chloride production at Westlake's other facilities, as well as industry capacity expansion in these downstream products in North America, a number of which have been recently completed.America. If Westlake is unable to generate sufficient cash flow from its operations to meet its obligations, or otherwise defaults on its obligations, under the Ethylene Sales Agreement, OpCo will not have sufficient available cash to distribute to us to enable us to pay the minimum quarterly distribution set forth in our cash distribution policy. As a result, our ability to pay the minimum quarterly distribution is based on the following factors, some of which are beyond our control:

•Westlake's inability to perform, or any other default on its obligations, under the Ethylene Sales Agreement, the Feedstock Supply Agreement, the Services and Secondment Agreement and the Omnibus Agreement;

•changes in insurance markets and the level, types and costs of coverage available, and the financial ability and willingness of our and Westlake's insurers to meet their obligations;

If OpCo is unable to renew or extend the Ethylene Sales Agreement beyond the initial 12-year initial term or the other agreements with Westlake upon expiration of these agreements, our ability to make distributions in the future could be materially adversely affected and the value of our units could decline.

Westlake's obligations under the Ethylene Sales Agreement, the Feedstock Supply Agreement and the related Services and Secondment Agreement continue in effect until December 31, 2026, after which such agreements will extend on an annual basis unless and until terminated by either party upon at least 12 months' prior written notice. In October 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. If OpCo were unable to reach agreement with Westlake on an extension or replacement of these agreements,agreements in the future, then our ability to make distributions on our common units could be materially adversely affected and the value of our common units could decline.

Additionally, certain of Westlake's employees in North America are represented by labor unions and works councils.unions. Our operations have been and may in the future be adversely affected by strikes, work stoppages and other labor disputes involving those employees that operate and maintain OpCo's ethylene production facilities and other assets. For example, on November 1, 2024, bargaining unit employees of Local Lodge No. 2781 of the IAM began a strike at our Calvert City, Kentucky facility, after the IAM members did not accept Westlake's final offer for a new collective bargaining agreement. The strike ended on November 8, 2024, after the IAM accepted Westlake's offer for a new collective bargaining agreement. Any future strikes or work stoppages could be significant and have an adverse effect on our financial condition and results of operations.

CostWe reimbursementsare dueobligated to reimburse our general partner and Westlake for services provided to us or on our behalfbehalf, which may reduce our earnings and therefore our cash available for distribution to our unitholders. The amount and timing of such reimbursements are determined by our general partner.

Our strategyability to grow our business and increase distributions to unitholders is dependent on our ability to make acquisitions that result in an increase in our cash distributions per unit. If we are unable to make acquisitions of additional interests in OpCo from Westlake on acceptable terms or we are unable to obtain financing for these acquisitions, our future growth and ability to increase distributions will be limited. In addition, we may be unable to make acquisitions from third parties as an alternative avenue to growth. Furthermore, even if we do consummate acquisitions that we believe will be accretive, they may in fact result in a decrease in our cash distributions per unit. Any acquisition involves potential risks, some of which are beyond our control, including, among other things:

Our operations also produce greenhouse gas ("GHG") emissions, which have been the subject of increased scrutiny and regulation. In December 2015, the United States joined the international community at the 21st Conference of the Parties of the United Nations Framework Convention on Climate Change in Paris, France. The resulting Paris Agreement calls for the parties to undertake "ambitious efforts" to limit the average global temperature and to conserve and enhance sinks and reservoirs of greenhouse gases. The United States signed the Paris Agreement in April 2016, and the Paris Agreement went into effect in November 2016. In November 2019, the United States submitted formal notification to the United Nations that it intended to withdraw from the Paris Agreement. The withdrawal took effect in November 2020. However, President Biden signed an executive order on January 20, 2021 for reentry of the United States into the Paris Agreement and on February 19, 2021, President Biden formally rejoined the Paris Agreement. As part of rejoining the Paris Agreement, President Biden announced that the United States would commit to a 50 to 52 percent reduction from 2005 levels of GHG emissions by 2030 and set the goal of reaching net-zero GHG emissions by 2050. To measure progress towards this target, the Paris Agreement requires the parties to complete a global stocktake, assessing members' collective efforts and achievements in reducing GHG emissions and adapting to the impacts of climate change, every five years. On December 13, 2023, the 28th annual United Nations Climate Change Conference ("COP 28"), which was held in Dubai, issued its first global stocktake, which calls on parties, including the United States, to contribute to the transitioning away from fossil fuels, reduce methane emissions, and increase renewable energy capacity, among other things, to achieve net zero emissions by 2050. Such meetings continued during the 29th annual United Nations Climate Change Conference, which was held in Baku, Azerbaijan in November 2024, and during COP 30, which was held in Belém, Brazil in November 2025. In January 2025, the United States submitted formal notification to the United Nations thatof itits intendsintention to withdraw from the Paris Agreement. Pursuant to the terms of the Paris Agreement, the withdrawal will taketook effect in January 2026. Legislation to regulate GHG emissions has periodically been introduced in the United States Congress, and such legislation may be proposed or adopted in the future. There has been a wide-ranging policy debate regarding the impact of these gases and possible means for their regulation. Some of the proposals would require industries to meet stringent new standards that would require substantial reductions in carbon emissions. The adoption and implementation of any international, federal or state legislation or regulations that restrict emissions of GHGs could result in increased compliance costs or additional operating restrictions. The EPA has adopted rules requiring the reporting of GHG emissions from specified large GHG emission sources on an annual basis including our facilities in Lake Charles and Calvert City. Various jurisdictions have considered or adopted laws and regulations on GHG emissions, with the general aim of reducing such emissions. The EPA currently requires certain industrial facilities to report their GHG emissions and to obtain permits with stringent control requirements before constructing or modifying new facilities with significant criteria pollutant and GHG emissions. As our chemical processing results in GHG emissions, these and other GHG laws and regulations could affect our costs of doing business.

On March 6, 2024, the U.S. Securities and Exchange Commission ("SEC") adopted a new set of rules that require a wide range of climate-related disclosures, including material climate-related risks, information on any climate-related targets or goals that are material to the registrant's business, results of operations, or financial condition, Scope 1 and Scope 2 GHG emissions on a phased-in basis by certain larger registrants when those emissions are material and the filing of an attestation report covering the same, and disclosure of the financial statement effects of severe weather events and other natural conditions including costs and losses. Multiple lawsuits have been filed challenging the SEC's new climate rules, and on April 4, 2024, the SEC issued an order staying the final rules until judicial review is complete. The SEC's final climate-related disclosure rules remain stayed pending resolution of judicial challenges and further action by the SEC. In September 2023, California passed climate-related disclosure mandates that are broader than the SEC's rules. Multiple lawsuits have been filed challenging California's climate-related disclosure rules. As our chemical processing results in GHG emissions, these and other environmental disclosure laws and regulations could affect our costs of doing business.

In November 2025, Westlake hasannounced that in 2024 it successfully met its publicly announced adisclosed target 20%to reduction inreduce its Scope 1 and Scope 2 CO2 equivalent emissions intensity per ton of production by 203020% from a 2016 baseline. Having reached its initial 2030 emissions target, Westlake announced a new target to further reduce its Scope 1 and Scope 2 CO2 equivalent emissions intensity per ton of production by an additional 5% by 2030, using a 2024 baseline. Developing and implementing plans for compliance with voluntary climate commitments can lead to additional capital, personnel, operations and maintenance expenditures and could significantly affect the economic position of existing facilities and proposed projects. Westlake's failure or perceived failure to pursue or fulfill its sustainability-focused goals, targets and objectives within the timelines announced, or at all, could adversely affect our business or reputation, as well as expose us to potential government enforcement actions and private litigation. We cannot predict the ultimate impact of achieving Westlake's emissions reduction goal, or the various implementation aspects, on our financial condition and results of operations.

The Board of Governors of the Federal Reserve System increased benchmark interest rates four times in 2023 and lowered benchmark interest rates threesix times in 2024.2024 and 2025. However, rates remain above the ten-year average and may rise in future periods. Should interest rates increase significantly, the amount of cash required to service our debt would increase. As a result, significant increases in interest rates could have a material impact on our financial position, results of operations and cash flows.

If at any time our general partner and its affiliates own more than 80% of the common units, our general partner will have the right, which it may assign to any of its affiliates or to us, but not the obligation, to acquire all, but not less than all, of the common units held by unaffiliated persons at a price equal to the greater of (1) the average of the daily closing price of the common units over the 20 trading days preceding the date three days before notice of exercise of the call right is first mailed and (2) the highest per-unit price paid by our general partner or any of its affiliates for common units during the 90-day period preceding the date such notice is first mailed. As a result, unitholders may be required to sell their common units at an undesirable time or price and may not receive any return or a negative return on their investment. Unitholders may also incur a tax liability upon a sale of their units. Our general partner is not obligated to obtain a fairness opinion regarding the value of the common units to be repurchased by it upon exercise of the limited call right. There is no restriction in our partnership agreement that prevents our general partner from causing us to issue additional common units and then exercising its call right. If our general partner exercised its limited call right, the effect would be to take us private and, if the units were subsequently deregistered, we would no longer be subject to the reporting requirements of the Securities Exchange Act of 1934, as amended,amended or (the "Exchange Act.Act").

Members of the investment community are increasing their focus on sustainability practices and disclosures by public companies, including practices and disclosures related to climate change and sustainability, D&I initiatives and heightened governance standards. On March 6, 2024, the SEC adopted a new set of rules that require a wide range of climate-related disclosures, including material climate-related risks. Multiple lawsuits have been filed challenging the SEC's new climate rules, and on April 4, 2024, the SEC issued an order staying the final rules until judicial review is complete. The SEC's final climate-related disclosure rules remain stayed pending resolution of judicial challenges and further action by the SEC. In September 2023, California passed climate-related disclosure mandates that are broader than the SEC's rules. Multiple lawsuits have been filed challenging California's climate-related disclosure rules. As a result, we may continue to face increasing pressure regarding our sustainability disclosures and practices. Additionally, members of the investment community may screen companies such as ours for sustainability disclosures and performance before investing in our common units. Over the past few years, there has also been an acceleration in investor demand for sustainability investing opportunities, and many large institutional investors have committed to increasing the percentage of their portfolios that are allocated towards sustainability investments. With respect to any of these investors, our sustainability disclosures and efforts may not satisfy the investor requirements or their requirements may not be made known to us. If we or our securities are unable to meet the sustainability standards or investment criteria set by these investors and funds, we may lose investors or investors may allocate a portion of their capital away from us, our cost of capital may increase, and our common unit price may be negatively impacted.

Our tax treatment depends on our status as a partnership for U.S. federal income tax purposes, and not being subject to a material amount of entity-level taxation. If the Internal Revenue Service ("IRS"),IRS, were to treat us as a corporation for U.S. federal income tax purposes, or we become subject to entity-level taxation for state tax purposes, our cash available for distribution to our unitholders would be substantially reduced.

The present U.S. federal income tax treatment of publicly-traded partnerships, including us, or an investment in our common units, may be modified by administrative, legislative or judicial changes or differing interpretations at any time. Members of Congress and the President have frequently proposed and considered substantive changes to the existing U.S. federal income tax laws that would affect publicly-traded partnerships, including proposals that would eliminate our ability to qualify for partnership tax treatment. RecentAlthough proposalsPub. haveL. No. 119-21, commonly known as "The One Big Beautiful Bill Act" (the "OBBBA"), which President Trump signed into law on July 4, 2025, provided for the expansion of the qualifying income exception for publicly traded partnerships in certain circumstances andcircumstances, other proposals have provided for the total elimination of the qualifying income exception upon which we rely for our partnership tax treatment. Further, while unitholders of publicly traded partnerships are, subject to certain limitations, entitled to a deduction equal to 20% of their allocable share of a publicly traded partnership's "qualified business income," this deduction is scheduled to expire with respect to taxable years beginning after December 31, 2025.

In general, we are entitled to a deduction for interest paid or accrued on indebtedness properly allocable to our trade or business during our taxable year. However, our deduction for "business interest" is limited to the sum of our business interest income and 30% of our "adjusted taxable income." For the purposes of this limitation, our adjusted taxable income is computed without regard to any business interest expense or business interest income. In the case of taxable years beginning on or after January 1, 2022, our adjusted taxable income is computed by taking into account any deduction allowable for depreciation, amortization, or depletion.

Moreover, the transferee of an interest in a partnership that is engaged in a U.S. trade or business is generally required to withhold 10% of the "amount realized" by the transferor unless the transferor certifies that it is not a foreign person. While the determination of a partner's "amount realized" generally includes any decrease of a partner's share of the partnership's liabilities, the Treasury Regulations provide that the "amount realized" on a transfer of an interest in a publicly-traded partnership, such as our common units, will generally be the amount of gross proceeds paid to the broker effecting the applicable transfer on behalf of the transferor, and thus will be determined without regard to any decrease in that partner's share of a publicly-traded partnership's liabilities. For a transfer of interests in a publicly traded partnership that is effected through a broker on or after January 1, 2023,broker, the obligation to withhold is imposed on the transferor's broker. Current and prospective non-U.S. unitholders should consult their tax advisors regarding the impact of these rules on an investment in our common units.

We generate revenue primarily by selling ethylene and the resulting co-products we produce. OpCo and Westlake have entered into an ethylene sales agreement (the "Ethylene Sales Agreement") pursuant to which we generate a substantial majority of our revenue. The Ethylene Sales Agreement is a long-term, fee-based agreement with a minimum purchase commitment and includes variable pricing based on OpCo's actual feedstock and natural gas costs and estimated other costs of producing ethylene (including OpCo's estimated operating costs and a five-year average of OpCo's expected future maintenance capital expenditures and other turnaround expenditures based on OpCo's planned ethylene production capacity for the year), plus a fixed margin per pound of $0.10 less revenue from co-products sales. Pursuant to the Ethylene Sales Agreement, Westlake'sWestlake obligationis obligated to pay for the annual minimum commitmentquantity (95% of OpCo's budgeted ethylene production), which is measured on an annual basis, is not reduced for a force majeure event lasting fewer than 45 consecutive days.days.In Inthe event Westlake purchases less than its annual commitment, we recognize a buyer deficiency fee ("Buyer Deficiency Fee") representing fixed margin and all expenses and expenditures incurred per pound of volume committed but not taken by Westlake. The annual commitment is not reduced for a force majeure event affecting OpCo's plants that lasts fewer than 45 consecutive days; however, in the event of such a force majeure event, we recognize buyera deficiencyBuyer feesDeficiency Fee representing fixed margin and unavoided operating and maintenance capital expenditures and maintenance expenses per pound of volume committed by Westlake during the force majeure period. InPayment of the eventBuyer WestlakeDeficiency purchases less than its annual commitment, we recognize buyer deficiency fees representing fixed margin and all expenses and expenditures incurred per pound of volume committed but not taken by Westlake. Payment for the buyer deficiency feeFee is scheduled to be received by the Partnership after the conclusion of the year.year in which the annual commitment was not purchased and taken by Westlake.Westlake has an option to take 95% of volumes in excess of the minimum commitment on an annual basis under the Ethylene Sales Agreement if we produce more than our planned production. Under the Ethylene Sales Agreement, the price for the sale of such excess ethylene to Westlake is based on a formula similar to that used for the minimum purchase commitment, with the exception of certain fixed costs.

Please refer to Note 22, "Agreements with Westlake and Related Parties," to theConsolidated consolidatedFinancial financial statementsStatements included in Item 8 of this form 10-K for more information on the Ethylene Sales Agreement.

OpCo hasis enteredparty intoto a 12-year feedstock supply agreement (the "Feedstock Supply Agreement") with Westlake Petrochemicals LLC, a wholly owned subsidiary of Westlake, under which Westlake Petrochemicals LLC supplies OpCo with ethane and other feedstocks that OpCo uses to produce ethylene under the Ethylene Sales Agreement. For its approximately 5% merchant sales, OpCo may purchase the ethane and other feedstocks to produce ethylene and resulting co-products to sell to unrelated third parties from Westlake Petrochemicals LLC. On October 28, 2025, OpCo and Westlake agreed to renew the Feedstock Supply Agreement through December 31, 2027 in accordance with its terms, which 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.

Please refer to Note 22, "Agreements with Westlake and Related Parties," to theConsolidated consolidatedFinancial financial statementsStatements included in Item 8 of this form 10-K for more information on the Feedstock Supply Agreement.

Our management seeks to maximize the profitability of our operations by effectively managing operating expenses, maintenance capital expenditures and turnaround costs. Our operating expenses are comprised primarily of feedstock costs and natural gas, labor expenses (including contractor services), utility costs (other than natural gas) and turnaround and maintenance expenses. With the exception of feedstock (including natural gas) and utilities-related expenses, operating expenses generally remain relatively stable across broad ranges of production volumes but can fluctuate from period to period depending on the circumstances, particularly maintenance and turnaround activities. Our maintenance capital expenditures and turnaround costs are comprised primarily of maintenance of our ethylene production facilities and the amortization of capitalized turnaround costs. These capital expenditures relate to the maintenance and integrity of our facilities. We capitalize the costs of major maintenance activities, or turnarounds, and amortize the costs over the period until the next planned turnaround of the affected facility. We commenced the next maintenance turnaround at Petro 1 in the first quarter of 2025.

The body of accounting principles generally accepted in the United States is commonly referred to as "GAAP." For this purpose, a non-GAAP financial measure is generally defined by the Securities and Exchange Commission ("SEC") as a numerical measure of a registrant's historical or future financial performance, financial position or cash flows that (1) excludes amounts, or is subject to adjustments that have the effect of excluding amounts, that are included in the most directly comparable measure calculated and presented in accordance with GAAP in the statement of income, balance sheet or statement of cash flows (or equivalent statements) of the registrant; or (2) includes amounts, or is subject to adjustments that have the effect of including amounts, that are excluded from the most directly comparable measure so calculated and presented. We use the non-GAAP measures of MLP distributable cash flow and EBITDA to analyze our performance. We define MLP distributable cash flow as net income plus depreciation, amortization and disposition of property, plant and equipment, less contributions for turnaround reserves, maintenance capital expenditures and mark-to-market adjustment on derivative contracts. We define MLP distributable cash flow as distributable cash flowcontracts less distributable cash flow attributable to Westlake's noncontrolling interest in OpCo and distributions attributable to the incentive distribution rights holder. There were no mark-to-market adjustments on derivative contracts or distributions attributable to the incentive distribution rights holder during the years ended December 31, 2024 or 2025. MLP distributable cash flow does not reflect changes in working capital balances. We define EBITDA as net income before interest expense, income taxes, depreciation and amortization. We use each of MLP distributable cash flow and EBITDA to analyze our performance. FeesBuyer forDeficiency a buyer deficiencyFee and Shortfall are included in net income in the periods in which they are recognized. MLP distributable cash flow and EBITDA are non-GAAP supplemental financial measures that management and external users of our consolidated financial statements, such as industry analysts, investors, lenders and rating agencies, may use to assess our operating performance as compared to other publicly-traded partnerships; our ability to incur and service debt and fund capital expenditures; and the viability of acquisitions and other capital expenditure projects and the returns on investment of various investment opportunities.

The table below and descriptions that follow represent the consolidated results of operations of the Partnership for the years ended December 31, 20242025 and 2023. A detailed comparison of the Partnership's 2023 operating results to its 2022 operating results can be found in the Management's Discussion and Analysis of Financial Condition and Results of Operations section in the Partnership's 2023 Annual Report on Form 10-K filed February 28, 2024.

For the year ended December 31, 2024,2025, net income was $298.6 million on net sales of $1,166.7 million. This represents a decrease in net income of $70.6 million as compared to net income of $369.2 million on net sales of $1,135.9 million. This represents an increase in net income of $34.6 million as compared to net income of $334.6 million on net sales of $1,190.8 million for the year ended December 31, 2023.2024. Net income attributable to the Partnership in 20242025 was $62.4$48.7 million as compared to $54.3$62.4 million in 2023,2024, ana increasedecrease of $8.1$13.7 million. Income from operations was $319.6 million for 2025, as compared to $390.4 million for 2024, asa compared to $357.7 million for 2023, an increasedecrease of $32.7$70.8 million. Net sales for 20242025 decreasedincreased by $54.9$30.8 million as compared to 20232024 primarily due to lowerhigher ethylene sales prices to Westlake in 20242025 comparedas towell 2023,as includinga theBuyer impactDeficiency Fee of $5.8 million from an annual production deficiency as a result of the salePetro of1 excessturnaround quantitiesextending ofinto ethyleneApril 2025, which was later than the planned completion in 2024March at prices that excluded certain non-variable costs of production pursuant to the Ethylene Sales Agreement,2025, partially offset by higherlower ethylene and co-products sales volumes to Westlake and higherthird third-partyparties ethyleneas salesa prices.result of lower production volumes attributable to the Petro 1 turnaround. Income from operations, net income and net income attributable to the Partnership for 20242025 increaseddecreased compared to 20232024 due to higher third-party ethylenelower sales prices,volumes lowerand higher ethane feedstock and natural gas costs and higher ethylene and co-products sales volumes,costs, partially offset by lowerhigher ethylene sales prices to Westlake including the impact of the sale of excess quantities of ethylene at prices that excluded certain non-variable costs of production.Westlake.

Net Sales. Net sales decreasedincreased by $54.9$30.8 million, or 4.6%,2.7%, to $1,166.7 million in 2025 from $1,135.9 million in 2024 from $1,190.8 million in 2023.2024. The decreaseincrease in net sales in 20242025 was primarily due to lowerhigher ethylene sales prices to Westlake in 20242025 as compared to 20232024 includingas thewell impactas a Buyer Deficiency Fee of $5.8 million from an annual production deficiency as a result of the salePetro of1 excessturnaround quantitiesextending ofinto ethyleneApril at2025, priceswhich thatwas excludedlater certainthan non-variablethe costsplanned ofcompletion production,in March 2025, partially offset by higherlower ethylene and co-products sales volumes to Westlake and higherthird third-partyparties ethyleneas salesa prices.result Lowerof lower production volumes attributable to the Petro 1 turnaround. Higher average sales prices in 20242025 contributed to a 6.6%10.4% increase in net sales compared to 2024. Lower sales volumes in 2025 contributed to an 8.2% decrease in net sales compared to 2023. Higher sales volumes in 2024 contributed to a 2.0% increase in net sales compared to 2023.2024.

Gross Profit. Gross profit was $418.9$347.8 million in 2024,2025 as compared to gross profit of $387.5$418.9 million in 2023.2024. The gross profit margin was 36.9%29.8% in 20242025 as compared to 32.5%36.9% in 2023.2024. The increaseddecreased gross profit margin in 20242025 was primarily due to lowerhigher ethane feedstock and natural gas costs and higher third-party ethylene sales prices in 20242025 as compared to 2023.2024.

InterestSelling, Expense—Westlake.General Interestand expenseAdministrative Expenses. Selling, general and administrative expenses remained relatively consistent at $25.7$28.3 million in 20242025 as compared to $26.5$28.5 million in 2023.2024.

Other Income, net. Other income, net increaseddecreased by $1.1$2.9 million to $2.4 million in 2025 from $5.3 million in 2024 from $4.2 million in 2023 primarily due to ana increasedecrease in interest earned on the balanceinvestments with Westlake under the Investment Management Agreement due to a higherlower average amount of cash invested and lower interest rates in 20242025 as compared to 2023.2024.

Provision for Income Taxes. Provision for income taxes remained relatively consistent at $0.8$0.5 million in 20242025 as compared to $0.8 million in 2023.2024.

EBITDA. EBITDA increaseddecreased by $35.5$57.6 million to $450.0 million in 2025 from EBITDA of $507.6 million in 2024 from EBITDA of $472.1 million in 2023.2024. The increaseddecrease in EBITDA, as compared to the prior year, was primarily due to higher third-party ethylene sales prices, lower ethane feedstock and natural gas costs and higherlower ethylene and co-products sales volumes into 2024Westlake and third parties as compareda result of lower production volumes in 2025 attributable to 2023,the Petro 1 turnaround, partially offset by lowerhigher ethylene sales prices to Westlake includingas thewell impactas a Buyer Deficiency Fee of $5.8 million from an annual production deficiency as a result of the salePetro of1 excessturnaround quantitiesextending ofinto ethyleneApril at2025, priceswhich thatwas excludedlater certainthan non-variablethe costsplanned ofcompletion production.in March 2025.

Operating activities provided cash of $485.0$280.5 million in 20242025 as compared to cash provided by operating activities of $452.0$485.0 million in 2023.2024. The $33.0$204.5 million increasedecrease in cash flows from operating activities was mainly due to highercash used in connection with the Petro 1 turnaround, lower income from operations,operations whichin was2025 partiallyas offsetcompared byto 2024 and a decrease in cash provided by working capital. Changes in components of working capital, which we define for the purposes of this cash flow discussion as accounts receivable, net—Westlake, accounts receivable, net—third parties, inventories, prepaid expenses and other current assets less accounts payable—Westlake, accounts payable—third parties and accrued and other liabilities, providedused cash of $24.8$23.7 million in 20242025 as compared to $34.4$24.8 million of cash provided in 2023,2024, resulting in a unfavorable change of $9.6$48.5 million. The unfavorable change in working capital was mainly attributable to an unfavorable changeschange in accrued and other liabilities andnet accounts payablereceivable—third parties primarilyWestlake due to higherthe maintenanceBuyer costsDeficiency accrualFee recognized in 2025 and lower receivables with Westlake outstanding as of the fourth quarter of 2024 due to sales of excess quantities of ethylene at Decembera 31,lower 2023sales asprice. compared to December 31, 2024. TheseThis unfavorable changeschange werewas partially offset by a favorable change in accountsaccrued receivable,and net—thirdother partiesliabilities due to collectionthe impact of athe maintenancePetro cost1 reimbursementturnaround activities and lower third party receivables at the endtiming of 2024.payments.

Net cash usedprovided forby investing activities during 20242025 was $89.0$31.2 million as compared to net cash used for investing activities of $75.9$89.0 million in 2023.2024, resulting in an overall favorable change of $120.2 million in investing cash flows. The $13.1favorable million increasechange in cash used for investing activities was mainlyprimarily due to ana increasedecrease in net cash invested under the Investment Management AgreementAgreement. During 2025, there were investments with Westlake of $10.0 million and maturities of investments with Westlake of $120.0 million under the Investment Management Agreement, whereas during 2024 there were investments with Westlake of $40.0 million and no maturities under the Investment Management Agreement. Capital expenditures increased to $78.8 million in 20242025 as compared to 2023. During 2024, we invested $40.0 million with Westlake. During 2023, we invested $174.1 million with Westlake, and $145.0 million of such investments matured. Capital expenditures were $49.0 million in 2024 as compareddue to $46.8the millionPetro in1 2023.turnaround. Capital expenditures duringin 2025 and 2024 andwere 2023 wereprimarily related to projects to improveincrease production capacity or reduce costs, maintenance costs and safety and environmental projects at our facilities.

In order to fund non-annual turnaround expenditures, we cause OpCo to reserve an amount for turnaround costs during each twelve-month period designed to cover future turnaround activities. Each of OpCo's ethylene production facilities requires turnaround maintenance approximately every five to eight years. By reserving additional cash annually, we intend to reduce the variability in OpCo's cash flow. Although we had previously planned to commence the next maintenance turnaround at the Petro 1 ethylene unit in the third quarter of 2024, we made the decision to defer the planned turnaround in order to maintain production and capitalize on higher average third-party ethylene sales prices during the third quarter of 2024. We commenced the planned maintenance turnaround in the first quarter of 2025. Westlake's purchase price for its minimum commitment of ethylene purchased under the Ethylene Sales Agreement includes a component (adjusted annually) designed to cover, over the long term, substantially all of OpCo's turnaround expenditures.

Critical accounting policies are those that are important to our financial condition and require management's most difficult, subjective or complex judgments. Different amounts would be reported under different operating conditions or under alternative assumptions. We have evaluated the accounting policies used in the preparation of the accompanying consolidated financial statements and related notes and believe those policies are reasonable and appropriate. Our significant accounting policies are summarized in Note 11, "Description of Business and Significant Accounting Policies," in the Notes to Consolidated Financial Statements in Item 8 of this form 10-K.

Additional information concerning long-lived assets and related depreciation and amortization appears in NotesNote 55, "Property, Plant and 7Equipment," and Note 7, "Deferred Charges and Other Assets," to theConsolidated consolidatedFinancial financial statementsStatements included in Item 8 of this form 10-K.

Environmental and Legal Obligations. We consult with various professionals to assist us in making estimates relating to environmental costs and legal proceedings. We accrue an expense when we determine that it is probable that a liability has been incurred and the amount is reasonably estimable. While we believe that the amounts recorded in the accompanying consolidated financial statements related to these contingencies are based on the best estimates and judgments available, the actual outcomes could differ from our estimates. Additional information about certain legal proceedings and environmental matters appears in "Item 1. Business—Environmental" and in Note 1616, "Commitments and Contingencies," to theConsolidated consolidatedFinancial financial statementsStatements included in Item 8 of this form 10-K.

The Partnership has conditional asset retirement obligations for the removal and disposal of hazardous materials and the remediation of the cause of any such release from certain of the Partnership's manufacturing facilities. However, no asset retirement obligations have been recognized because the fair value of the conditional legal obligation cannot be measured due to the indeterminate settlement date of the obligation. SettlementAs such, the impact of the settlement of these conditional asset retirement obligations is not expected to have a material adverse effect on the Partnership's financial condition, results of operations or cash flows in any individual reporting period.period cannot be determined at this time.

See Note 11, "Description of Business and Significant Accounting Policies," to theConsolidated consolidatedFinancial financial statementsStatements included in Item 8 of this form 10-K for a full description of recent accounting pronouncements, including expected dates of adoption and estimated effects on results of operations and financial condition, which is incorporated herein by reference.

For the quartersix months ended MarchJune 31,30, 2026, net income was $81.7$164.0 million on net sales of $305.7$602.8 million. This represents an increase in net income of $39.4$35.9 million as compared to net income of $42.3$128.1 million on net sales of $237.6$534.7 million for the quartersix months ended MarchJune 31,30, 2025. Net income attributable to the Partnership for the firstsix quartermonths ofended June 30, 2026 was $14.2$28.4 million as compared to $4.9$19.5 million for the firstsix quartermonths ofended June 30, 2025, an increase of $9.3$8.9 million. Income from operations was $86.6$173.9 million for the firstsix quartermonths ofended June 30, 2026 as compared to $46.6$137.8 million for the firstsix quartermonths ofended June 30, 2025, an increase of $40.0$36.1 million. Net sales for the first quarter of 2026 increased by $68.1 million as compared to the first quarter of 2025. These increases were primarily driven by higher ethylene production and resulting higher sales to Westlake in the first quarter of 2026 as compared to lower ethylene production due to the Petro 1 turnaround in the first quarter of 2025. In addition, we had higher co-products sales volumes, which was partially offset by lower sales prices and lower ethylene sales volumes to third parties. Higher incomeIncome from operations, net income and net income attributable to the Partnership for the firstsix quartermonths ofended June 30, 2026 as compared to the firstsix quartermonths ofended 2025June 30, 2025, were higher primarily due to the higher ethylene sales to Westlake and higher co-products sales during the six months ended June 30, 2026, as compared to the six months ended June 30, 2025. Net sales for the six months ended June 30, 2026 increased by $68.1 million as compared to net sales for the six months ended June 30, 2025, mainly due to higher ethylene sales volumes to Westlake wasand third parties as well as higher co‑products sales volumes, partially offset by higherlower naturalsales gasprices. costsThe increase in sales volumes in the firstsix quartermonths ofended 2026June 30, 2026, as compared to the firstsix quartermonths ofended 2025.June 30, 2025 was due to increased production in the current period as the prior year comparative period production volume was negatively impacted by the Petro 1 turnaround.

FirstSecond Quarter 2026 Compared with FirstSecond Quarter 2025

Net Sales. Net sales increasedremained byconsistent $68.1at million, or 28.7%, to $305.7$297.1 million in the firstsecond quarter of 2026, compared to $297.1 million in the second quarter of 2025. Net sales in the second quarter of 2025 included a buyer deficiency fee from Westlake of $13.6 million. Excluding the effect of the buyer deficiency fee, net sales increased by $13.6 million, or 4.8%, in the second quarter of 2026 fromas $237.6compared million into the firstsecond quarter of 2025. The increase in net sales infrom the firstprior‑year quarter of 2026 as compared to the first quarter of 2025period was primarily due to higher ethylene sales volumes to Westlake and third parties, as well as higher co‑products sales volumes, partially offset by lower sales prices andproduct sales volumes to third parties.parties, partially offset by the effect of lower average sales prices to Westlake. Higher sales volumes in the firstsecond quarter of 2026 contributed to a 36.4%9.0% increase in net sales compared to the firstsecond quarter of 2025.2025, Lowerwhile lower average sales prices in the firstsecond quarter of 2026 contributed to a 7.7%4.2% decrease in net sales compared to the firstsecond quarter of 2025.

Gross Profit. Gross profit increaseddecreased to $93.8$94.8 million in the firstsecond quarter of 2026 from $54.1$97.5 million in the firstsecond quarter of 2025. Gross profit margin in the firstsecond quarter of 2026 was 30.7%,31.9%, as compared to 22.8%32.8% in the firstsecond quarter of 2025. The highermarginally lower gross profit margin was primarily due to higher production andlower sales prices in the firstsecond quarter of 2026 as compared to the first quarter of 2025 due to the Petro 1 turnaround in the firstsecond quarter of 2025, partially offset by higherlower naturalfeedstock gasand costsfuel in the first quarter of 2026 compared to the first quarter of 2025.costs.

Selling, General and Administrative Expenses. Selling, general and administrative expenses remainedincreased relativelyby consistent$1.2 atmillion $7.2or 19.0% to $7.5 million in the firstsecond quarter of 2026 as compared to $7.5$6.3 million in the firstsecond quarter of 2025. The increase was mainly attributable to higher service costs in the second quarter of 2026 as compared to the second quarter of 2025.

Interest Expense—Westlake. Interest expense of $5.1 million in the firstsecond quarter of 2026 decreased from $5.5$5.9 million in the firstsecond quarter of 2025 mainly due to lower interest rates on the outstanding debt in the firstsecond quarter of 2026 as compared to the firstsecond quarter of 2025.

Other Income, net. Other income, net decreased to $0.3 million in the firstsecond quarter of 2026 from $1.3$0.7 million in the firstsecond quarter of 2025, primarily due to a decrease in interest earned on investments with Westlake under the Investment Management Agreement due to a lower average amount of cash invested and lower interest rates in the firstsecond quarter of 2026 as compared to the firstsecond quarter of 2025.

MLP Distributable Cash Flow. MLP distributable cash flow increased by $13.2$2.6 million to $17.9$17.6 million in the firstsecond quarter of 2026 from $4.7$15.0 million in the firstsecond quarter of 2025. The increase in the first quarter of 2026, as compared to the prior-year period, was primarily attributable to increasedhigher earningsproduction atand OpCosales volumes and lower maintenance capital expenditures in the firstsecond quarter of 2026.2026 as a result of the prior year’s Petro 1 turnaround.

EBITDA. EBITDA increaseddecreased by $46.2$1.7 million to $121.2$122.7 million in the firstsecond quarter of 2026 from $75.0$124.4 million in the firstsecond quarter of 2025. The increasedecrease was primarily due to higherlower ethylene sales prices to Westlake and higher co-products sales, partially offset by higher natural gas costs in the firstsecond quarter of 2026 compared to the firstsecond quarter of 2025.

CASH FLOW DISCUSSION FOR THE THREESIX MONTHS ENDED MARCHJUNE 31,30, 2026 AND 2025

Operating activities provided cash of $110.2$240.0 million in the first threesix months of 2026 compared to cash provided by operating activities of $45.8$54.9 million in the first threesix months of 2025. The $64.4$185.1 million increase in cash flows from operating activities was mainly due to higher income from operations in the first threesix months of 2026 as compared to the first threesix months of 2025 and a favorable impact in the first threesix months of 2026 as compared to the first threesix months of 2025 when significant cash was used in connection with the 2025 Petro 1 turnaround,turnaround offsetand byan a decreaseincrease in cash provided by working capital changes. Changes in components of working capital resulted in cash useinflow of $5.4$3.3 million in the first threesix months of 2026 as compared to $81.7$10.6 million of cash providedused in the first threesix months of 2025, resulting in an overall unfavorablefavorable change of $87.1$13.9 million. The unfavorablefavorable change in working capital was mainly attributable to a favorable change in net accounts receivable—Westlake. This favorable change was partially offset by unfavorable changes in accounts payable—third parties and accrued and other liabilities. This unfavorable change was partially offset by a favorable change in net accounts receivable—Westlakeliabilities in the first threesix months of 2026.

Net cash used for investing activities in the first threesix months of 2026 was $18.6$38.0 million as compared to net cash provided by investing activities of $14.0$49.7 million in the first threesix months of 2025, resulting in an overall unfavorable change of $32.6$87.7 million in investing cash flows. During the first threesix months of 2026, there were investments of $13.0$20.0 million with Westlake and no maturities of investments with Westlake under the Investment Management Agreement, whereas during the first threesix months of 2025, there were no investments with Westlake and there were maturities of $30.0$90.0 million. Capital expenditures decreased to $5.6$18.0 million in the first threesix months of 2026 as compared to $16.0$40.3 million in the first threesix months of 2025 due to the 2025 Petro 1 turnaround. Capital expenditures in the first threesix months of 2026 and 2025 were primarily related to projects to increase production capacity or reduce costs, maintenance costs and safety and environmental projects at our facilities.

Net cash used for financing activities in the first threesix months of 2026 was $91.6$197.0 million as compared to net cash used for financing activities of $68.5$126.3 million in the first threesix months of 2025. The cash outflows in the first threesix months of 2026 were related to distributions of $75.0$163.7 million to the noncontrolling interest retained in OpCo by Westlake and of $16.6$33.2 million to unitholders by the Partnership. The cash outflows in the first threesix months of 2025 were related to distributions of $51.9$93.0 million to the noncontrolling interest retained in OpCo by Westlake and of $16.6$33.2 million to unitholders by the Partnership.

Pursuant to the terms of the Equity Distribution Agreement, entered in October 2018 and amended in February 2020, among the Partnership and various investment banks, the Partnership may offer and sell the Partnership's common units from time to time to or through the investment banks, as the Partnership's sales agents or as principals, having an aggregate offering amount of up to $50.0 million (the "ATM Program"). The Partnership intends to use the net proceeds of sales of the common units, if any, for general partnership purposes, which may include the funding of potential drop-downs and other acquisitions. No common units had been issued under the ATM Program as of MarchJune 31,30, 2026.

On MayAugust 4,3, 2026, the board of directors of Westlake Chemical Partners GP LLC, our general partner, approved a quarterly distribution of $0.4714 per common unit payable on JuneAugust 1,28, 2026 to unitholders of record as of MayAugust 14,13, 2026, which equates to a total amount of approximately $16.6 million per quarter, or approximately $66.5 million per year in aggregate, based on the number of common units outstanding on MarchJune 31,30, 2026. We do not have a legal or contractual obligation to pay distributions on a quarterly basis or any other basis at our minimum quarterly distribution rate or any other rate.

Westlake has historically funded expansion capital expenditures related to Lake Charles Olefins and Calvert City Olefins. No such funding was required by OpCo during the threesix months ended MarchJune 31,30, 2026 and 2025. Total capital expenditures for the threesix months ended MarchJune 31,30, 2026 and 2025 were $5.6$18.0 million and $16.0$40.3 million, respectively. We expect that Westlake will loan additional cash to OpCo to fund its expansion capital expenditures in the future, but Westlake is under no obligation to do so.

As of MarchJune 31,30, 2026, our cash and cash equivalents totaled $44.3$49.3 million. In addition, we have cash invested under the Investment Management Agreement (as described below) and a revolving credit facility with Westlake available to supplement cash if needed, as described under "Indebtedness" below.

In August 2017, the Partnership, OpCo and Westlake executed the Investment Management Agreement that authorizes 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. The Partnership had $36.4$43.6 million of cash invested under the Investment Management Agreement at MarchJune 31,30, 2026.

In connection with the IPO, OpCo entered into a $600.0 million revolving credit facility with an affiliate of Westlake, as amended in June 2017, September 20182018, July 2022 and July 20222026 (the "OpCo Revolver") that may be used to fund growth projects and working capital needs. The OpCo Revolver is scheduled to mature on July 12,11, 2027.2031. On July 12,8, 2022,2026, OpCo entered into the SecondThird Amendment (the "OpCo Revolver Amendment") to the OpCo Revolver. The OpCo Revolver Amendment, among other things,Amendment extended the maturity date to July 12,11, 20272031 and provided forremoved the replacement0.10% ofcredit spread adjustment that had previously applied to the LondonOpCo InterbankRevolver's OfferedSOFR-based Rateinterest ("LIBOR") with the Secured Overnight Financing Rate, as administered by the Federal Reserve Bank of New York ("SOFR").rate. Borrowings under the OpCo Revolver now bear interest at a variable rate of either (a) SOFR plus the Applicable Margin plus a 0.10% credit spread adjustment or, if SOFR is no longer available, (b) the Alternate Base Rate plus the Applicable Margin minus 1.0%. The Applicable Margin under the OpCo Revolver is 1.75%. As of MarchJune 31,30, 2026, outstanding borrowings under the OpCo Revolver totaled $22.6 million and bore interest at SOFR plus the Applicable Margin and credit spread adjustment, which is accrued in arrears quarterly.

In 2015, we entered into a senior, unsecured revolving credit agreement with an affiliate of Westlake, as amended in August and November 2017, March 20202020, July 2022 and July 20222026 (the "MLP Revolver"). The MLP Revolver has a borrowing capacity of $600.0 million and is scheduled to mature on July 12,11, 2027.2031. On July 12,8, 2022,2026, the Partnership entered into the FourthFifth Amendment (the "MLP Revolver Amendment") to the MLP Revolver. The MLP Revolver Amendment, among other things,Amendment extended the maturity date to July 12,11, 20272031 and provided forremoved the replacement0.10% ofcredit LIBORspread withadjustment SOFRthat ashad previously applied to the referenceMLP Revolver's SOFR-based interest rate. Borrowings under the MLP Revolver now bear interest at a variable rate of either (a) SOFR plus the Applicable Margin plus a 0.10% credit spread adjustment or, if SOFR is no longer available, (b) the Alternate Base Rate plus the Applicable Margin minus 1.0%. The Applicable Margin under the MLP Revolver varies between 1.75% and 2.75%, depending on the Partnership's Consolidated Leverage Ratio. The MLP Revolver provides that we may pay all or a portion of the interest on any borrowings in kind, in which case any such amounts would be added to the principal amount of the loan. The MLP Revolver requires that we maintain a consolidated leverage ratio of either (1) during any one-year period following certain types of acquisitions (including acquisitions of additional interests in OpCo), 5.50:1.00 or less, or (2) during any other period, 4.50:1.00 or less. The MLP Revolver also contains certain other customary covenants. The repayment of borrowings under the MLP Revolver is subject to acceleration upon the occurrence of an event of default. As of MarchJune 31,30, 2026, outstanding borrowings under the MLP Revolver totaled $377.1 million and bore interest at SOFR plus the Applicable Margin and credit spread adjustment, which is accrued in arrears quarterly. We intend to use the MLP Revolver to purchase additional limited partnership interests in OpCo in the future, in the event OpCo desires to sell such additional interests to us, for other acquisitions and for general partnership purposes.