X0306 4 2021-11-19 0 0000879407 ARROWHEAD PHARMACEUTICALS, INC. ARWR 0001794629 San Martin Javier 177 E. COLORADO BLVD SUITE 700 PASADENA CA 91105 0 1 0 0 Chief Medical Officer Common Stock 2021-11-19 4 S 0 13704 69.01 D 116796 D Common Stock 2021-11-19 4 S 0 5696 70.01 D 111100 D Common Stock 2021-11-19 4 S 0 100 70.99 D 111000 D Open market sale pursuant to a 10b5-1 trading plan adopted by the Reporting Person in accordance with Rule 10b5-1 of the Securities Exchange Act of 1934, as amended. The sale was made to generate proceeds to cover the tax liability incident to the vesting of restricted stock units. The price reported on Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $68.54 to $69.53, inclusive. The reporting person undertakes to provide to Arrowhead Pharmaceuticals, Inc., any security holder of Arrowhead 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 this footnote of this Form 4. The price reported on Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $69.54 to $70.36, inclusive. The reporting person undertakes to provide to Arrowhead Pharmaceuticals, Inc., any security holder of Arrowhead 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 this footnote of this Form 4. Includes previously reported shares of common stock underlying Restricted Stock Units granted to the Reporting person which are subject to certain vesting conditions. /s/Javier San Martin 2021-11-22