X0306 4 2023-03-15 0001177648 ENANTA PHARMACEUTICALS INC ENTA 0001571212 Or Yat Sun C/O ENANTA PHARMACEUTICALS, INC. 500 ARSENAL STREET WATERTOWN MA 02472 0 1 0 0 Sr. VP & CSO Common Stock 2023-03-15 4 M 0 13925 14 A 388627 D Common Stock 2023-03-15 4 S 0 269 43.92 D 388358 D Common Stock 2023-03-15 4 S 0 13656 44.46 D 374702 D Stock Option (Right to Buy) 14 2023-03-15 4 M 0 13925 0 D 2023-03-21 Common Stock 13925 0 D The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person in November 2022. The price reported in Column 4 is a weighted-average price. These shares were sold in multiple transactions at prices ranging from $43.86 to $43.96, inclusive. The price reported in Column 4 is a weighted-average price. These shares were sold in multiple transactions at prices ranging from $44.02 to $45.00, inclusive. On March 21, 2013, the reporting person was granted an option to purchase 41,763 shares of common stock, half of which became exercisable upon the achievement of several clinical milestones during the four-year performance period after the date of grant. The reporting person undertakes to provide to Enanta Pharmaceuticals, Inc., any security holder of Enanta 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 footnotes 2 and 3 above. /s/ Nathaniel S. Gardiner as attorney-in-fact 2023-03-17