Westlake Chemical Partners LP

Explanatory Note

Unless otherwise indicated, references in this Annual Report on Form 10-K (this "report") to "we," "our," "us" or like terms refer to Westlake Chemical Partners LP ("Westlake Chemical Partners LP" or the "Partnership"), Westlake Chemical OpCo LP ("OpCo") and Westlake Chemical OpCo GP LLC ("OpCo GP"). References to "Westlake" refer to Westlake Corporation and its consolidated subsidiaries other than the Partnership, OpCo GP and OpCo. Unless the context otherwise requires, references to our "board of directors" or our "directors" refer to the board of directors of our general partner and such board's directors, respectively.

Cautionary Statement Regarding Forward-Looking Statements

Certain of the statements contained in this report are forward-looking statements. All statements, other than statements of historical facts, included in this report that address activities, events or developments that we expect, project, believe or anticipate will or may occur in the future are forward-looking statements. Forward-looking statements can be identified by the use of words such as "believes," "intends," "may," "should," "could," "anticipates," "expects," "will" or comparable terminology, or by discussions of strategies or trends. Although we believe that the expectations reflected in such forward-looking statements are reasonable, we cannot give any assurances that these expectations will prove to be correct. Forward-looking statements relate to matters such as:

•the ultimate timing, outcome and results of our strategies and plans;

•the amount of ethane that we are able to process, which could be adversely affected by, among other things, operating difficulties;

•the volume of ethylene that we are able to sell;

•the price at which we are able to sell ethylene;

•industry market outlook, including prices and margins in third-party ethylene and co-products sales;

•widespread outbreak of an illness or any other communicable disease, or any other public health crisis;

•the impact of ongoing supply chain constraints caused by the conflicts in the Middle East and between Russia and Ukraine;

•the parties to whom we will sell ethylene and on what basis;

•volumes of ethylene that Westlake may purchase, in addition to the minimum commitment under the Ethylene Sales Agreement;

•timing, funding and results of capital expenditures;

•our intended quarterly distributions and the manner of making such distributions;

•our ability to meet our liquidity needs;

•timing of and amount of capital expenditures;

•our At-the-Market program and the use of any net proceeds from any sales under that program;

•our and OpCo's ability to extend our credit agreements with Westlake;

•potential loans from Westlake to OpCo to fund OpCo's expansion capital expenditures in the future;

•expected mitigation of exposure to commodity price fluctuations;

•turnaround activities and the variability of OpCo's cash flow;

•receipt of any Buyer Deficiency Fee and Shortfall under the Ethylene Sales Agreement;

•compliance with present and future environmental regulations and costs associated with environmentally related penalties, capital expenditures, remedial actions and proceedings, including any new laws, regulations or treaties that may come into force to limit or control carbon dioxide and other greenhouse gas emissions or to address other issues of climate change;

•our ability to receive indemnification from Westlake for environmental and other losses; and

•effects of pending legal proceedings.

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We have based these statements on assumptions and analysis in light of our experience and perception of historical trends, current conditions, expected future developments and other factors we believe were appropriate in the circumstances when the statements were made. Forward-looking statements by their nature involve substantial risks and uncertainties that could significantly impact expected results, and actual future results could differ materially from those described in such statements. These statements are subject to a number of assumptions, risks and uncertainties, including those described in "Part 1. Item 1A. Risk Factors" of this report and the following:

•general economic and business conditions, including inflation, interest rates and possible recession;

•the cyclical nature of the chemical industry;

•the availability, cost and volatility of raw materials and energy;

•lower crude oil prices reducing the cost advantage of ethane-based ethylene producers;

•actions taken by Westlake, including the renewal or renegotiation of, or determinations made pursuant to, our contractual arrangements with Westlake;

•uncertainties associated with the United States and worldwide economies, including those due to political tensions and conflict in the Middle East and elsewhere, including the conflict between Russia and Ukraine;

•uncertainties associated with pandemic infectious diseases;

•uncertainties associated with climate change;

•the potential impact on demand for ethylene due to initiatives such as recycling and customers seeking alternatives to polymers;

•current and potential governmental regulatory actions in the United States and regulatory actions and political unrest in other countries, including environmental regulations;

•industry production capacity and operating rates;

•the supply/demand balance for our products;

•competitive products and pricing pressures;

•instability in the credit and financial markets;

•access to capital markets;

•terrorist acts;

•operating interruptions (including leaks, explosions, fires, weather-related incidents, mechanical failure, unscheduled downtime, delays in turnaround activities, labor difficulties, transportation interruptions, spills and releases and other environmental risks);

•changes in laws or regulations;

•the effects of government shutdowns;

•technological developments;

•information systems failures and cyberattacks;

•our ability to implement our business strategies; and

•creditworthiness of our customers.

Many of these factors are beyond our ability to control or predict. Any of the factors, or a combination of these factors, could materially affect our future results of operations and the ultimate accuracy of the forward-looking statements. These forward-looking statements are not guarantees of our future performance, and our actual results and future developments may differ materially from those projected in the forward-looking statements. Management cautions against putting undue reliance on forward-looking statements or projecting any future results based on such statements or present or prior earnings levels. Every forward-looking statement speaks only as of the date of the particular statement, and we undertake no obligation to publicly update or revise any forward-looking statements.

Industry and Market Data

Industry and market data used throughout this report were obtained through internal research, surveys and studies conducted by unrelated third parties and publicly available industry and general publications. We have not independently verified market and industry data from external sources. While we believe internal partnership estimates are reliable and market definitions are appropriate, neither such estimates nor these definitions have been verified by any independent sources.

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Production Capacity

Unless we state otherwise, annual production capacity estimates used throughout this report represent rated capacity of the facilities at December 31, 2025. We calculated rated capacity by estimating the number of days in a typical year that a production unit of a plant is expected to operate, after allowing for downtime for regular maintenance, and multiplying that number by an amount equal to the unit's optimal daily output based on the design feedstock mix. Because the rated capacity of a production unit is an estimated amount, actual production volumes may be more or less than the rated capacity.

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