144 0001619961 XXXXXXXX LIVE 0001582313 Xenon Pharmaceuticals Inc. 001-36687 3650 Gilmore Way Burnaby A1 V5G 4W8 (604)-484-3300 IAN MORTIMER Officer Director Common Shares Canaccord Genuity Corp.

1133 Melville St Suite 1200 Vancouver, BC Z4 V6E 4E5

270000 16289196 83190316 03/09/2026 NASDAQ Common Shares 03/09/2026 Exercise of Options Issuer N 270000 03/09/2026 Cash N Ian Mortimer

3650 Gilmore Way Burnaby A1 V5G 4W8

Common Shares 01/02/2026 40000 1777166 The Common Shares reported on this Form 144 were obtained via the exercise of options scheduled to expire between March 12, 2027 and September 15, 2029, and are being sold pursuant to a Rule 10b5-1 trading plan. 03/09/2026 09/27/2024 /s/ Ian Mortimer