X0508 4 2026-02-19 0001262823 WESTLAKE CORP WLK 0002064540 Szwejbka Scott Thomas 2801 POST OAK BLVD., SUITE 600 HOUSTON TX 77056 false true false false SVP, HIP Segment Head false Common Stock 2026-02-19 4 A false 365 0 A 13864 D Common Stock 2026-02-20 4 F false 91 94.10 D 13773 D Employee Option (right to buy) 94.48 2026-02-20 4 A false 14595 0 A 2036-02-20 Common Stock 14595 14595 D Restricted Stock Units 2026-02-20 4 A false 3983 0 A Common Stock 3983 3983 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. 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. Scott T. Szwejbka by J. Feng, POA 2026-02-23