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

14375 647360 77275005 12/05/2025 NASDAQ Common Shares 05/24/2023 Exercise of Options Issuer N 35282 05/24/2023 Net exercise N Ian Mortimer

3650 Gilmore Way Burnaby Z4 V5G 4W8

Common Shares 10/01/2025 25000 1004117 Ian Mortimer

3650 Gilmore Way Burnaby Z4 V5G 4W8

Common Shares 11/28/2025 97 4366 The Common Shares reported on this Form 144 are being sold pursuant to a Rule 10b5-1 trading plan. 12/05/2025 09/27/2024 /s/ Ian Mortimer