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

40000 1777166.23 77275005 01/02/2026 NASDAQ Common Shares 01/02/2026 Exercise of Options Issuer N 40000 01/02/2026 Cash N Ian Mortimer

3650 Gilmore Way Burnaby Z4 V5G 4W8

Common Shares 11/28/2025 97 4366 Ian Mortimer

3650 Gilmore Way Burnaby Z4 V5G 4W8

Common Shares 12/05/2025 14375 647360 Ian Mortimer

3650 Gilmore Way Burnaby A1 V5G 4W8

Common Shares 12/08/2025 10830 495248 The Common Shares reported on this Form 144 were obtained via the exercise of options scheduled to expire on March 10, 2026, and are being sold pursuant to a Rule 10b5-1 trading plan. 01/02/2026 09/27/2024 /s/ Ian Mortimer