Westlake Corporation (NYSE: WLK) (“Westlake”) (the “Company”) announced today that the Company has approved a plan to cease operation of certain of the Company’s North American chlorovinyl production facilities, including: its polyvinyl chloride (“PVC”) plant at the Aberdeen, Mississippi site, which has an annual capacity of approximately 1 billion pounds of suspension PVC resin; its vinyl chloride monomer (“VCM”) plant at the Lake Charles, Louisiana North site, which has an annual capacity of approximately 910 million pounds of VCM; and one of its diaphragm chlor-alkali units at the Lake Charles, Louisiana South site, which has an annual capacity of approximately 825 million pounds of chlorine and 910 million pounds of caustic soda. The Company plans to continue supplying customers with PVC, VCM and chlor-alkali products from its seven other North American chlorovinyl facilities. Following the closures, the Company expects to have aggregate annual production capacity of approximately

Westlake Corporation (NYSE: WLK) today released its 2024 Sustainability Report , marking the company’s eighth consecutive annual update on its voluntary sustainability initiatives and ongoing operational improvements. The report highlights that Westlake has successfully met its target to reduce Scope 1 and Scope 2 CO 2 e emissions per ton of production by 20% compared to its 2016 baseline. “At Westlake, we are deeply committed to sustainability and continuous improvement. Achieving our goal of reducing Scope 1 and Scope 2 CO 2 e emissions per ton of production by 20% from our 2016 baseline reflects the dedication and innovative spirit of our entire team,” said Jean-Marc Gilson, President and Chief Executive Officer at Westlake Corporation. “This milestone demonstrates our ongoing efforts to drive meaningful change for our business, our communities, and the environment.” Having reached its initial 2030 emissions target, Westlake is now committed to further decreasing its Scope 1 and

$0.53 per share dividend declared payable on December 11, 2025 The Board of Directors of Westlake Corporation (NYSE: WLK) today declared a regular dividend distribution of $0.53 per share for the third quarter of 2025. This dividend will be payable on December 11, 2025 to stockholders of record on November 25, 2025. Westlake announced its first dividend on November 11, 2004 and has successively been paying and increasing its dividend for the past 21 years. The statements in this release that are not historical facts, including statements regarding future payment of dividend, are forward-looking statements. These forward-looking statements are subject to significant risks and uncertainties. For more detailed information about the factors that could cause actual results to differ materially, please refer to Westlake’s Annual Report on Form 10-K for the year ended December 31, 2024, which was filed with the SEC in February 2025, and Westlake’s Quarterly Report on Form 10-Q for the

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