X0306 4 2021-05-27 0 0001582313 Xenon Pharmaceuticals Inc. XENE 0000938801 HOLLER FRANK A 200 - 3650 GILMORE WAY BURNABY A1 V5G 4W8 BRITISH COLUMBIA, CANADA 1 0 0 0 Common Shares 2021-05-27 4 M 0 3086 3.76 A 125127 D Common Shares 2021-05-27 4 F 0 507 18.88 D 124620 D Common Shares 2021-05-27 4 M 0 36008 3.76 A 160628 D Common Shares 2021-05-27 4 F 0 5911 18.88 D 154717 D Common Shares 2021-05-27 4 S 0 2579 18.69 D 152138 D Common Shares 2021-05-27 4 S 0 8485 18.68 D 143653 D Common Shares 1184 I Spouse Stock Option (Right to Buy) 3.76 2021-05-27 4 M 0 3086 0.00 D 2021-05-28 Common Shares 3086 0 D Stock Option (Right to Buy) 3.76 2021-05-27 4 M 0 36008 0.00 D 2021-05-28 Common Shares 36008 0 D The exercise price was converted from $3.74 CAD using the closing rate of exchange of the Bank of Canada on the date of grant. The actual exercise price is the Canadian dollar amount regardless of the exchange rate on the date of exercise. Represents the closing price of the Company's common shares on May 26, 2021, which was converted to a Canadian dollar amount for purposes of net settlement calculations. The "Amount" and "Price" reported in this Column 4 reflect the aggregate number and weighted-average price, respectively, of shares sold. These shares were sold in multiple transactions at prices ranging from $18.51 to $18.92, inclusive. The reporting person undertakes to provide to the issuer, any security holder of the issuer, or the SEC staff, upon request, full information regarding the number of shares sold at each separate price within the range set forth herein The "Amount" and "Price" reported in this Column 4 reflect the aggregate number and weighted-average price, respectively, of shares sold. These shares were sold in multiple transactions at prices ranging from $18.54 to $18.92, inclusive. The reporting person undertakes to provide to the issuer, any security holder of the issuer, or the SEC staff, upon request, full information regarding the number of shares sold at each separate price within the range set forth herein The shares subject to the option fully vested on December 31, 2013. The date the options became fully vested was incorrectly reflected on the Reporting Person's Form 3. Expiration date differs from originally reported date due to an automatic extension provided by the option plan as a result of the original expiration date falling during a Company blackout period and a lock-up agreement period. /s/ Cassandra Robinson, Attorney-in-fact 2021-06-01