X0508 4 2025-09-03 0 0000874015 IONIS PHARMACEUTICALS INC IONS 0001838539 Schneider Eugene 2855 GAZELLE COURT CARLSBAD CA 92010 0 1 0 0 EVP, Chf Clinical Develop Ofcr 1 Common Stock 2025-09-03 4 M 0 19658 53.77 A 71165 D Common Stock 2025-09-03 4 S 0 12455 60.4608 D 58710 D Common Stock 2025-09-03 4 S 0 7203 61.4163 D 51507 D Non-Qualified Stock Option (right to buy) 53.77 2025-09-03 4 M 0 19658 0.0 D 2020-01-02 2026-01-01 Common Stock 19658 0 D Shares sold pursuant to a Rule 10b5-1 Trading Plan adopted by the reporting person on May 2, 2025. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $60.1862 to $61.14 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. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $61.21 to $61.66 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 (3) on this Form 4. By: Patrick R. O'Neil, attorney-in-fact For: Eugene Schneider 2025-09-04