Transaction Details

Footnotes

Shares sold pursuant to a Rule 10b5-1 Trading Plan adopted by the reporting person on November 26, 2025. | The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $74.865 to $75.85 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 $75.88 to $76.17 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. | The reporting person disclaims beneficial ownership of all securities held by his son, and this report should not be deemed an admission that the reporting person is the beneficial owner of such securities for purposes of Section 16 or for any other purpose.