X0306 4 2022-04-01 0001177648 ENANTA PHARMACEUTICALS INC ENTA 0001646976 Adda Nathalie C/O ENANTA PHARMACEUTICALS, INC. 500 ARSENAL STREET WATERTOWN MA 02472 0 1 0 0 Sr. VP & Chief Medical Officer Common Stock 2022-04-01 4 M 0 16000 31.42 A 50982 D Common Stock 2022-04-01 4 M 0 31664 30.00 A 82646 D Common Stock 2022-04-01 4 M 0 2895 48.52 A 85541 D Common Stock 2022-04-01 4 S 0 8299 70.75 D 77242 D Common Stock 2022-04-01 4 S 0 42260 71.32 D 34982 D Common Stock 2022-04-04 4 M 0 6285 48.52 A 41267 D Common Stock 2022-04-04 4 M 0 9625 43.57 A 50892 D Common Stock 2022-04-04 4 M 0 16875 63.35 A 67767 D Common Stock 2022-04-04 4 S 0 2500 70.56 D 65267 D Common Stock 2022-04-04 4 S 0 18076 71.71 D 47191 D Common Stock 2022-04-04 4 S 0 3200 72.65 D 43991 D Common Stock 2022-04-04 4 S 0 9009 73.42 D 34982 D Stock Option (Right to Buy) 31.42 2022-04-01 4 M 0 16000 0 D 2025-11-20 Common Stock 16000 0 D Stock Option (Right to Buy) 30.00 2022-04-01 4 M 0 31664 0 D 2026-11-18 Common Stock 31664 0 D Stock Option (Right to Buy) 48.52 2022-04-01 4 M 0 2895 0 D 2027-11-17 Common Stock 2895 6285 D Stock Option (Right to Buy) 48.52 2022-04-04 4 M 0 6285 0 D 2027-11-17 Common Stock 6285 0 D Stock Option (Right to Buy) 43.57 2022-04-04 4 M 0 9625 0 D 2030-11-20 Common Stock 9625 21175 D Stock Option (Right to Buy) 63.35 2022-04-04 4 M 0 16875 0 D 2029-11-18 Common Stock 16875 13125 D The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person in December 2021 in contemplation of her previously announced retirement plan. The price reported in Column 4 is a weighted-average price. These shares were sold in multiple transactions at prices ranging from $70.12 to $71.00, inclusive. The price reported in Column 4 is a weighted-average price. These shares were sold in multiple transactions at prices ranging from $71.02 to $72.00, inclusive. The price reported in Column 4 is a weighted-average price. These shares were sold in multiple transactions at prices ranging from $70.06 to $70.99, inclusive. The price reported in Column 4 is a weighted-average price. These shares were sold in multiple transactions at prices ranging from $71.00 to $71.99, inclusive. The price reported in Column 4 is a weighted-average price. These shares were sold in multiple transactions at prices ranging from $72.00 to $72.99, inclusive. The price reported in Column 4 is a weighted-average price. These shares were sold in multiple transactions at prices ranging from $73.00 to $73.91, inclusive. 100% of the shares subject to the option are fully vested and exercisable. The option, representing a right to purchase a total of 30,800 shares, became or will become exercisable (subject to the optionholder's continued employment) quarterly in substantially equal installments (any fractional shares to be cumulated and to become exercisable at the end of the earliest succeeding quarterly period in which a whole share equivalent is accumulated) over four years from the date of grant (November 20, 2020). The option, representing a right to purchase a total of 30,000 shares, became or will become exercisable (subject to the optionholder's continued employment) quarterly in substantially equal installments (any fractional shares to be cumulated and to become exercisable at the end of the earliest succeeding quarterly period in which a whole share equivalent is accumulated) over four years from the date of grant (November 18, 2019). 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 through 7 above. /s/ Nathaniel S. Gardiner as attorney-in-fact 2022-04-05