X0306 4 2013-05-28 0 0001262823 WESTLAKE CHEMICAL CORP WLK 0001439749 Kenner Andrew 2801 POST OAK BLVD HOUSTON TX 77056 0 1 0 0 VP - Manufacturing Common Stock 2013-05-28 4 M 0 2893 20.525 A 14116 D Common Stock 2013-05-28 4 M 0 1523 60.105 A 15639 D Common Stock 2013-05-28 4 M 0 1263 45.830 A 16902 D Common Stock 2013-05-28 4 S 0 9607 94.1283 D 7295 D Employee Option (right to buy) 20.525 2013-05-28 4 M 0 2893 0 A 2013-02-26 2020-02-26 Common Stock 2893 0 D Employee Option (right to buy) 60.105 2013-05-28 4 M 0 1523 0 A 2013-02-17 2022-02-17 Common Stock 1523 3046 D Employee Option (right to buy) 45.83 2013-05-28 4 M 0 1263 0 A 2013-02-18 2021-02-18 Common Stock 1263 1263 D In accordance with the Securities and Exchange Commission's No Action Letter dated June 25, 2008, we have aggregated the sales that occurred on May 28, 2013 for ease of reporting. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $91.1000 to $94.2090, inclusive. The reporting person undertakes to provide to Westlake Chemical Corp., any security holder of Westlake Chemical Corp. or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in this footnote (1) to this Form 4. Andrew Kenner by Richard C. Kroger PoA 2013-05-30