X0508 4 2025-12-22 false 0001262823 WESTLAKE CORP WLK 0001299403 Chao Albert 2801 POST OAK BLVD., STE. 600 HOUSTON TX 77056 true true false false Executive Chairman false Common Stock 2025-12-22 4 M false 81673 44.42 A 668558 D Common Stock 2025-12-22 4 S false 9711 72.818 D 658847 D Common Stock 2025-12-22 4 S false 30604 73.796 D 628243 D Common Stock 2025-12-22 4 S false 521 74.443 D 627722 D Employee Option (right to buy) 44.42 2025-12-22 4 M false 81673 0 D 2026-02-18 Common Stock 81673 0 D A portion of the sale proceeds were used to cover the strike price and related taxes in regards to the excercise of the options disclosed in Table II. Weighted average price. These shares were sold in multiple transactions ranging from $72.395 to $73.39 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. Weighted average price. These shares were sold in multiple transactions ranging from $73.40 to $74.40 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. Weighted average price. These shares were sold in multiple transactions ranging from $74.405 to $74.515 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 exercisable in three installments of 33%, 33% and 34% on February 18, 2017, 2018 and 2019, respectively. Albert Chao by J Feng POA 2025-12-23