X0306 4 2021-09-16 0 0001785173 89bio, Inc. ETNB 0001792064 Waisbourd Ram C/O 89BIO, INC. 142 SANSOME STREET, 2ND FLOOR SAN FRANCISCO CA 94104 0 1 0 0 See Remarks Common Stock 2021-09-16 4 M 0 7000 1.93 A 7000 D Common Stock 2021-09-16 4 S 0 7000 19.46 D 0 D Stock Option (Right to Buy) 1.93 2021-09-16 4 M 0 7000 0.00 D 2028-11-09 Common Stock 7000 25203 D This transaction was executed pursuant to a Rule 10b5-1 trading plan in multiple trades at prices ranging from $19.18 to $20.06. The price reported above reflects the weighted average sales price. The reporting person hereby undertakes to provide upon request to the SEC staff, the Issuer or a security holder of the Issuer full information regarding the number of shares and prices at which the transaction was effected. This option represents a right to purchase a total of 102,203 shares of the Issuer's common stock, one quarter of which vested on May 1, 2019, with the remaining three quarters vesting in equal quarterly installments over the following three years. Chief Operating Officer and Chief Business Officer /s/ Ryan A. Murr, as attorney-in-fact for Ram Waisbourd 2021-09-20