X0306 4 2015-05-08 0 0001262823 WESTLAKE CHEMICAL CORP WLK 0001439749 Kenner Andrew 2801 POST OAK BOULEVARD, SUITE 600 HOUSTON TX 77056 0 1 0 0 VP - Manufacturing Common Stock 2015-05-06 4 M 0 6092 30.0525 A 18273 D Common Stock 2015-05-06 4 M 0 2526 22.915 A 20799 D Common Stock 2015-05-06 4 S 0 8618 72.269 D 12181 D Common Stock 2015-05-06 4 S 0 2161 72.3169 D 10020 D Employee Option (right to buy) 30.0525 2015-05-06 4 M 0 6092 0 D 2022-02-17 Common Stock 6092 0 D Employee Option (right to buy) 22.915 2015-05-06 4 M 0 2526 0 D 2021-02-18 Common Stock 2526 0 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 6, 2015 for ease of reporting. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $72.25 to $72.34, 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. 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 6, 2015 for ease of reporting. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $72.31 to $72.34, 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. The stock options are exercisable in three installments of 33%, 33% and 34% on February 17, 2013, 2014 and 2015, respectively. The stock options are exercisable in three installments of 33%, 33% and 34% on February 18, 2012, 2013 and 2014, respectively. Andrew Kenner by J. Iglesias POA 2015-05-08