Westlake Corporation (NYSE: WLK) (“Westlake”) today announced the expiration and results of its cash tender offer to purchase (the “Offer”) any and all of the outstanding 3.600% Senior Notes due 2026 (the “Notes”). The tender offer described herein was made on the terms and subject to the conditions set forth in the Offer to Purchase, dated November 4, 2025 (the “Offer to Purchase”) and the related Notice of Guaranteed Delivery. Capitalized terms used but not defined in this announcement have the meanings given to them in the Offer to Purchase. The tender offer expired at 5:00 p.m., New York City time, on November 10, 2025 (the “Expiration Date”). The settlement date for the Offer will be on or about November 12, 2025 (the “Settlement Date”). According to information provided by Global Bondholder Services Corporation, $253,730,000 aggregate principal amount of the Notes were validly tendered (other than pursuant to the guaranteed delivery procedures set forth in the Offer to Purchase

Westlake Corporation (NYSE: WLK) (“Westlake”) today announced the pricing of its cash tender offer to purchase (the “Offer”) any and all of the outstanding 3.600% Senior Notes due 2026 (the “Notes”) on the terms set forth in the table below. The table below sets forth the applicable Reference Yield and Consideration for the Notes, as calculated at 2:00 p.m., New York City time, today, November 10, 2025, in accordance with the Offer to Purchase (as defined below). Series of Notes CUSIP Numbers(1) Aggregate Principal Amount Outstanding U.S. Treasury Reference Security(2) Reference Yield Bloomberg Reference Page(2) Fixed Spread(2) Consideration(2) 3.600% Senior Notes due 2026 960413AT9 (Registered) 960413AH5 (Rule 144A) U96060AC9 (Reg. S) $750,000,000 4.375% UST due 8/15/2026 3.741% FIT3 35 bps $996.32 (1) No representation is made as to the correctness or accuracy of the CUSIP numbers listed in this press release. Such information is provided solely for the convenience of holders of the

Westlake Corporation (NYSE: WLK) announced that Westlake Polyethylene’s LDPE Sulphur, Louisiana manufacturing site has attained the globally-recognized International Sustainability & Carbon Certification (ISCC) PLUS certification. This achievement includes mass balance certification, recognizing the site’s robust systems for tracing and managing alternative raw materials throughout the polymer production process to advance sustainability goals. “The ISCC PLUS certification at our Polyethylene site in Sulphur, Louisiana is an important milestone in our commitment to deliver more sustainable solutions for our customers,” said Amy Moore, Vice President – Olefins & Polyethylene. “This certification recognizes our expanding portfolio of innovative polymers with recycled or renewable content in support of a circular economy. The ISCC PLUS certification confirms and helps accelerate our progress as an industry leader in producing polymers with attributed bio or circular content and

Westlake Corporation (NYSE: WLK) (“Westlake”) announced today that it has priced its previously announced underwritten public offering of $600,000,000 aggregate principal amount of senior unsecured notes due 2035 (the “2035 Notes”) and $600,000,000 aggregate principal amount of senior unsecured notes due 2055 (the “2055 Notes” and, together with the 2035 Notes, the “Notes”) under its existing shelf registration statement. The 2035 Notes will bear interest at a rate of 5.550% per annum and will mature on November 15, 2035. The 2055 Notes will bear interest at a rate of 6.375% per annum and will mature on November 15, 2055. The sale of the Notes is scheduled to close on November 6, 2025, subject to the satisfaction of customary closing conditions. Westlake intends to use the net proceeds from the proposed public offering of the Notes to fund the repurchase of its outstanding 3.600% Senior Notes due 2026 (the “2026 Senior Notes”) pursuant to a concurrent cash tender offer (the “Tender

Westlake Corporation (NYSE: WLK) (“Westlake”) announced today the commencement of a cash tender offer to purchase (the “Offer”) any and all of the outstanding 3.600% Senior Notes due 2026 (the “Notes”) as set forth in the table below. The tender offer is being made solely pursuant to the terms and conditions set forth in an Offer to Purchase, dated November 4, 2025 (the “Offer to Purchase”). Holders of the Notes are urged to carefully read the Offer to Purchase before making any decision with respect to the tender offer. The tender offer is not conditioned on any minimum amount of the Notes being tendered. Subject to applicable law, Westlake may amend, extend or terminate the tender offer in its sole discretion. Capitalized terms used but not defined in this announcement have the meanings given to them in the Offer to Purchase. Series of Notes CUSIP Numbers(1) Aggregate Principal Amount Outstanding U.S. Treasury Reference Security(2) Bloomberg Reference Page(2) Fixed Spread(3) 3.600%

Westlake Corporation (NYSE: WLK) (“Westlake”) announced today the commencement of an underwritten public offering, subject to market and other conditions, of senior unsecured notes (the “Notes”) under its existing shelf registration statement. The timing of pricing and terms of the Notes are subject to market conditions and other factors. Westlake intends to use the net proceeds from the proposed public offering of the Notes to fund the repurchase of its outstanding 3.600% Senior Notes due 2026 (the “2026 Senior Notes”) pursuant to a concurrent cash tender offer (the “Tender Offer”) for any and all of the 2026 Senior Notes. Westlake anticipates using any remaining net proceeds to fund the purchase price of its pending acquisition of the global compounding solutions businesses of the ACI/Perplastic Group (the “ACI Acquisition”) and for general corporate purposes, including working capital management. The offering of the Notes is not contingent upon the successful completion of the

Renewed Ethylene Sales Agreement through 2027 at existing terms Declared quarterly distribution of $0.4714 per unit; 45 th consecutive quarterly distribution Westlake Chemical Partners LP (NYSE: WLKP) (the "Partnership") today reported net income attributable to the Partnership in the third quarter of 2025 of $14.7 million, or $0.42 per limited partner unit, which was below third quarter 2024 net income of $18.1 million. Cash flows from operating activities in the third quarter of 2025 were $105.2 million, a decrease of $20.9 million compared to third quarter 2024 cash flows from operating activities of $126.1 million. For the three months ended September 30, 2025, MLP distributable cash flow was $14.9 million, a decrease of $3.0 million compared to third quarter 2024 MLP distributable cash flow of $17.9 million. The decrease in MLP distributable cash flow and associated trailing twelve-month coverage ratio was primarily due to higher maintenance capital expenditures. Third quarter

Westlake Corporation (NYSE: WLK) (the "Company" or "Westlake") today announced third quarter 2025 results. SUMMARY FINANCIAL HIGHLIGHTS (in millions of dollars, except per share data and percentages) Three Months Ended September 30, 2025 Three Months Ended June 30, 2025 Three Months Ended September 30, 2024 Westlake Corporation Net sales $ 2,838 $ 2,953 $ 3,117 Income (loss) from operations $ (766 ) $ (109 ) $ 180 Net income (loss) attributable to Westlake Corporation $ (782 ) $ (142 ) $ 108 Diluted earnings (loss) per common share $ (6.06 ) $ (1.11 )

Westlake Chemical Partners LP (NYSE: WLKP) (the “Partnership”) announced that Westlake Chemical OpCo LP (“OpCo”) and Westlake Corporation (“Westlake”) agreed to renew the Ethylene Sales Agreement between the parties through December 31, 2027 in accordance with its terms, which provides 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. The renewal of the Ethylene Sales Agreement will facilitate continued offtake on attractive terms for 95% of the ethylene produced by OpCo. The renewed agreement maintains the same pricing formula and sales volume protections that have provided the Partnership with the distributable cash flow to make 45 consecutive quarterly distributions to unitholders, without any decreases, since its initial public offering in 2014. In connection with the renewal of the Ethylene Sales Agreement, OpCo and certain affiliates of