X0508 4 2026-02-19 0001262823 WESTLAKE CORP WLK 0001330417 Bender Mark Steven 2801 POST OAK BLVD., STE. 600 HOUSTON TX 77056 false true false false EVP & CFO false Common Stock 2026-02-19 4 A false 1777 0 A 62287 D Common Stock 2026-02-20 4 F false 445 94.099 D 61842 D Employee Option (right to buy) 94.48 2026-02-20 4 A false 28389 0 A 2036-02-20 Common Stock 28389 28389 D Restricted Stock Units 2026-02-20 4 A false 7747 0 A Common Stock 7747 7747 D Represents shares of common stock that vested on February 19, 2026, upon the determination by the Compensation Committee of the Issuer's Board of Directors of the satisfaction of performance criteria underlying an award of performance stock units ("PSUs") granted to the Reporting Person on February 17, 2023, under the terms of the Issuer's 2013 Omnibus Incentive Plan. Shares otherwise issuable were witheld to satisfy tax obligations arising out of vesting of the Reporting Person's PSUs. Weighted average price. These shares were sold in multiple transactions at prices ranging from $93.98 to $94.10, inclusive. The Reporting Person undertakes to provide the Issuer, any security holder of the Issuer, or the staff of the SEC, upon request, full information regarding the number of shares sold at each separate price within the range set forth above. The stock options are excercisable in three installments of 33%, 33% and 34% on February 20, 2027, 2028 and 2029, respectively. Each restricted stock unit ("RSU") represents a contingent right to recieve one share of the Issuer's common stock. All of the RSUs will vest on February 20, 2029. Mark Steven Bender by J. Feng, POA 2026-02-23