X0306 4 2021-05-05 0 0001678660 Prelude Therapeutics Inc PRLD 0001621172 Mauro David J C/O PRELUDE THERAPEUTICS INCORPORATED 200 POWDER MILL ROAD WILMINGTON DE 19803 0 1 0 0 Chief Medical Officer Common Stock 2021-05-05 4 M 0 15000 1.89 A 15000 D Common Stock 2021-05-05 4 S 0 3415 39.3555 D 11585 D Common Stock 2021-05-05 4 S 0 10476 40.2967 D 1109 D Common Stock 2021-05-05 4 S 0 1109 41.0682 D 0 D Common Stock 1.89 2021-05-05 4 M 0 15000 0.00 D 2029-06-16 Common Stock 15000 212610 D The transactions reported on this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the reporting person. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $38.70 to $39.69, inclusive. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer, 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 herein. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $39.70 to $40.69, inclusive. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer, 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 herein. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $40.70 to $41.52, inclusive. The reporting person undertakes to provide to the Issuer, any security holder of the Issuer, 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 herein. The stock option vested as to 25% of the total shares monthly on May 1, 2020, and thereafter vests as to 1/48 of the total shares monthly until fully vested, subject to the Reporting Person's provision of service to the Issuer on the vesting date. /s/ Brian Piper, Attorney-in-Fact 2021-05-07