X0508 4 2025-11-25 0 0000874015 IONIS PHARMACEUTICALS INC IONS 0002037721 Devers Shannon L. 2855 GAZELLE COURT CARLSBAD CA 92010 0 1 0 0 EVP, Chief Human Resources Ofc 1 Common Stock 2025-11-25 4 M 0 16777 53.77 A 34271 D Common Stock 2025-11-25 4 S 0 16777 80.9109 D 17494 D Non-Qualified Stock Option (right to buy) 53.77 2025-11-25 4 M 0 16777 0.0 D 2020-01-02 2026-01-01 Common Stock 16777 0 D Shares sold pursuant to a Rule 10b5-1 Trading Plan adopted by the reporting person on September 3, 2024. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $80.66 to $81.14 inclusive. The reporting person undertakes to provide to Ionis Pharmaceuticals, Inc. any security holder of Ionis Pharmaceuticals, Inc. 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 footnote (2) on this Form 4. By: Patrick R. O'Neil, attorney-in-fact For: Shannon L. Devers 2025-11-28