Westlake Chemical Partners LP

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED STATEMENTS OF OPERATIONS

CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY

CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY

CONSOLIDATED STATEMENTS OF CASH FLOWS

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.

The Partnership owns a 22.8% 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 andone common carrier ethylene pipeline. The remaining 77.2% limited partner interest in OpCo is owned by Westlake Corporation. References to "Westlake" refer collectively to Westlake Corporation and its subsidiaries, other than the Partnership, OpCo and OpCo GP.

OpCo and Westlake entered into an ethylene sales agreement (the "Ethylene Sales Agreement") pursuant to which the Partnership generates a substantial majority of its revenue. For more information, see Note 8.

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, 2025 (the "2025 Form 10-K"), filed with the SEC on March 4, 2026. 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, 2025.

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, 2026, its results of operations for the three and nine months ended September 30, 2026 and 2025 and the changes in its cash position for the nine months ended September 30, 2026 and 2025.

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, 2026 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.

Revision of Related Party Disclosure

During the third quarter of 2026, the Partnership identified errors with respect to certain charges from Westlake that had been omitted from its previously reported related party cost of sales disclosures. The omission had no impact on the Partnership's previously reported consolidated balance sheets, statements of operations, statements of changes in equity or statements of cash flows. The Partnership concluded that the omission was not material to any previously issued financial statements. Refer to Note 8 for the amounts by period and the periods revised.

Recently Issued Accounting Pronouncement

Disaggregation of Income Statement Expenses (ASU No. 2024-03)

In November 2024, the Financial Accounting Standards Board ("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.

Recently Adopted Accounting Pronouncement

Measurement of Credit Losses for Accounts Receivable and Contract Assets (ASU No. 2025-05)

In July 2025, the 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 adopted the standard electing a practical expedient effective January 1, 2026, and the adoption of this accounting standard did not have a material impact on its consolidated statements of financial position, results of operations, or cash flows, or on related financial statement disclosures.

2. Accounts Receivable—Third Parties

Accounts receivable—third parties consisted of the following:

3. Inventories

Inventories consisted of the following:

4. Property, Plant and Equipment

Depreciation expense on property, plant and equipment of $20,396 and $21,966 is included in cost of sales in the consolidated statements of operations for the three months ended September 30, 2026 and 2025, respectively. Depreciation expense on property, plant and equipment of$65,648 and$64,389 is included in cost ofsales in the consolidated statements of operations for thenine months ended September 30, 2026 and 2025, respectively.

5. Deferred Charges and Other Assets

Amortization expense on deferred charges and other assets of $11,808 and $11,906 is included in cost of sales in the consolidated statements of operations for the three months ended September 30, 2026 and 2025, respectively. Amortization expense on deferred charges and other assets of$35,883 and $29,035 is included in cost of sales in the consolidated statements of operations for the nine months ended September 30, 2026 and 2025, respectively.

6. Distributions and Net Income Per Limited Partner Unit

On November 2, 2026, 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, 2026 of $0.4714 per common unit. This distribution is payable on December 1, 2026 to unitholders of record as of November 13, 2026.

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.

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, in the event distributions related to the incentive distribution rights are made, net income equal to the amount of those distributions would first be allocated to the general partner before the remaining net income would be 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.

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. Incentive distribution rights represent the right to receive increasing percentages (15.0 %,25.0 % and 50.0 %) of quarterly distributions from operating surplus after the target distribution levels have been achieved. 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:

If cash distributions to the Partnership's unitholders do not exceed $1.2938 per common unit in a quarter, then no distribution is made with respect to the Partnership's incentive distribution rights for such quarter. The Partnership's distribution for the three months ended September 30, 2026 was $0.4714 per common unit, which 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, 2026 and 2025 were as follows:

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. To date, no common units have been issued under this program.

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.

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, the 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 2025 consolidated financial statements included in the 2025 Form 10-K filed on March 4, 2026, 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 these 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 they charge Westlake a fee.

OpCo sells a significant portion of its ethylene production to Westlake. Sales to related parties were as follows:

As of September 30, 2026, OpCo's production resulted in expected "excess quantities" of ethylene produced based on annual estimated production. Pursuant to the terms of the Ethylene Sales Agreement, the excess quantities produced by the Partnership were sold to Westlake at prices that excluded certain fixed costs of production. The fixed cost of production associated with the estimated excess quantities for the nine months ended September 30, 2026 was approximately $4,900.

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 included in cost of sales were as follows:

(1)Revised. As previously disclosed, feedstock purchased from Westlake and included in cost of sales was $95,110 and $271,176, and other charges from Westlake and included in cost of sales were $33,952 and $99,158, for the three and nine months ended September 30, 2025, respectively. See Revision of Previously Reported Amounts below.

Revision of Previously Reported Amounts

During the third quarter of 2026, the Partnership identified that certain charges from Westlake had been omitted from its previously reported related party cost of sales disclosures. The amounts for the three and nine months ended September 30, 2025 in the table above have been revised.

The following tables present the amounts by which the previously disclosed amounts for other periods were understated:

There was no impact to the Partnership's consolidated balance sheets, statements of operations, statements of changes in equity or statements of cash flows. The impact to all previously reported interim and annual periods was not material. The amounts for the nine months ended September 30, 2026 include the corrected amounts for the first and second quarters of 2026. The amounts for the years ended December 31, 2024 and 2025, the three months ended March 31, 2026 and the three and six months ended June 30, 2026 will be revised when those periods are presented in future filings.

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:

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:

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 $544 and $206 was included in the receivable under the Investment Management Agreement balance at September 30, 2026 and December 31, 2025, respectively. Total interest earned related to the Investment Management Agreement was $544 and $224 for the three months ended September 30, 2026 and 2025, respectively, and $1,218 and $2,333 for the nine months ended September 30, 2026 and 2025, respectively.

The Partnership's receivable under the Investment Management Agreement was as follows:

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 recognized under the Ethylene Sales Agreement.

As of December 31, 2025, OpCo had 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. The Buyer Deficiency Fee is measured periodically based upon the lower of the actual production deficiency at period end or the estimated annual production deficiency based upon OpCo's annual anticipated production. These periodic estimates are updated at the end of the year based on actual annual production. The Buyer Deficiency Fee is classified as a component of net sales—Westlake. The total Buyer Deficiency Fee recognized by the Partnership during the twelve months ended December 31, 2025 was $5,835. The Buyer Deficiency Fee recognized in 2025 was received by the Partnership in January 2026.

The Partnership's accounts receivable from Westlake were as follows:

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:

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 $556 and $468 for the three months ended September 30, 2026 and 2025, respectively, and $1,474 and $1,246 for the nine months ended September 30, 2026 and 2025, respectively, and are reflected in other charges from Westlake that are included in cost of sales.

OpCo hastwo site lease agreements with Westlake, each of which has a term of 50 years. Pursuant to the site lease agreements, OpCo pays Westlakeone 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, 2026 and 2025 was $5,110 and $5,947, respecti vely. Interest on related party debt payable balances, net of capitalized interest, for thenine months ended September 30, 2026 and 2025 was $15,314 and$17,391, respectively. Interest on related party debt payable is presented as interest expense—Westlake in the consolidated statements of operations. At September 30, 2026 and December 31, 2025, accrued interest on related party debt was $5,110 and $5,508, 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:

Major Customer and Concentration of Credit Risk

During the three months ended September 30, 2026 and 2025, Westlake accounted for approximately 83.3% and 89.5%, respectively, of the Partnership's net sales. During thenine months ended September 30, 2026 and 2025, Westlake accounted for approximately 83.2% and 87.3%, respectively, of the Partnership's net sales.

9. Long-Term Debt

Long-term debt payable to Westlake consisted of the following:

On July 8, 2026, OpCo entered into the Third Amendment to the OpCo Revolver and the Partnership entered into the Fifth Amendment to the MLP Revolver. These amendments extended the maturity dates of the OpCo Revolver and the MLP Revolver from July 12, 2027 to July 11, 2031 and removed the 0.10% credit spread adjustments that had previously applied to the SOFR‑based interest rates under the OpCo Revolver and the MLP Revolver.

As of September 30, 2026, 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. 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. As of September 30, 2026, the OpCo Revolver and the MLP Revolver were scheduled to mature on July 11, 2031.

The weighted average interest rate on all long-term debt was 5.5% and 5.8% at September 30, 2026 and December 31, 2025, respectively.

As of September 30, 2026, 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, 2026 and December 31, 2025 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.

11. Supplemental Information

Accrued and Other Liabilities

Accrued and other liabilities were $21,420 and $22,199 at September 30, 2026 and December 31, 2025, respectively. Accrued taxes, accrued interest on related party debt and accrued capital expenditures, which are components of accrued and other liabilities, were $6,227, $5,110 and $3,205, respectively, at September 30, 2026 and $2,104, $5,508 and $994, respectively, at December 31, 2025. 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 $8,835 and $5,768 at September 30, 2026 and 2025, respectively.

Operating Leases

Right-of-use assets obtained in exchange for operating lease obligations were $460 and $920 for the nine months ended September 30, 2026 and 2025, 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.

13. Segment Information

The Partnership hasone 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.

A reconciliation of total segment net income to consolidated net income is as follows:

(1)Other segment items include interest expense—Westlake, other income, net and provision for income taxes.