X0306 4/A 2022-01-31 2021-07-07 0 0001745999 Beam Therapeutics Inc. BEAM 0001786304 Evans John M. C/O BEAM THERAPEUTICS INC. 238 MAIN STREET CAMBRIDGE MA 02142 1 1 0 0 CEO Common Stock 980825 D Common Stock 2021-11-16 5 G 0 E 12000 0.00 D 968825 D Common Stock 2022-01-31 4 S 0 801 63.79 D 968024 D Common Stock 2022-01-31 4 S 0 2172 64.47 D 965852 D Common Stock 2022-01-31 4 S 0 3177 65.49 D 962675 D Common Stock 2022-01-31 4 S 0 6337 66.55 D 956338 D Common Stock 2022-01-31 4 S 0 13535 67.44 D 942803 D Common Stock 2022-01-31 4 S 0 3978 68.15 D 938825 D Common Stock 2022-01-31 4 M 0 100000 1.03 A 1038825 D Common Stock 2022-01-31 4 S 0 300 63.45 D 182700 I By John M. Evans, III 2018 Irrevocable Trust Common Stock 2022-01-31 4 S 0 1615 64.46 D 181085 I By John M. Evans, III 2018 Irrevocable Trust Common Stock 2022-01-31 4 S 0 1900 65.55 D 179185 I By John M. Evans, III 2018 Irrevocable Trust Common Stock 2022-01-31 4 S 0 4105 66.48 D 175080 I By John M. Evans, III 2018 Irrevocable Trust Common Stock 2022-01-31 4 S 0 9408 67.43 D 165672 I By John M. Evans, III 2018 Irrevocable Trust Common Stock 2022-01-31 4 S 0 2672 68.16 D 163000 I By John M. Evans, III 2018 Irrevocable Trust Stock Option (Right to Buy) 1.03 2028-07-13 Common Stock 384345 D Stock Option (Right to Buy) 1.03 2022-01-31 4 M 0 100000 0.00 D 2028-07-13 Common Stock 100000 284345 D Stock Option (Right to Buy) 69.21 2022-01-31 4 A 0 112500 0.00 A 2032-01-31 Common Stock 112500 112500 D On each of July 7, 2021 and October 6, 2021, the reporting person filed a Form 4 which inadvertently reported an exercise of stock options in connection with certain sales of common stock. In fact, the reporting person did not exercise any stock options in connection with the sales reported on such Forms 4. Accordingly, the first line of each of Tables 1 and 2 of this Form 4 reflects the corrected number of securities beneficially owned by the reporting person prior to the transactions reported herein. The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan. The sale price reported is a weighted average price. The reporting person undertakes to provide to Beam Therapeutics Inc. ("BEAM"), any security holder of BEAM 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 range. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $63.60 to $63.96, inclusive. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $64.21 to $64.50, inclusive. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $65.20 to $65.99, inclusive. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $66.09 to $66.94, inclusive. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $67.00 to $67.99, inclusive. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $68.00 to $68.60, inclusive. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $63.26 to $63.58, inclusive. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $64.17 to $64.50, inclusive. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $65.20 to $65.99, inclusive. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $66.00 to $66.94, inclusive. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $67.00 to $67.99, inclusive. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $68.00 to $68.60, inclusive. The option vests as to 25% on the first anniversary of the of the vesting commencement date, January 8, 2018, and at a rate of 2.78% each month thereafter until the option is fully vested. The option vests in equal monthly installments each month following the date of grant for the subsequent 48 months, subject to the reporting person's continued service with BEAM through each vesting date. By: /s/ Christine Bellon, Attorney-in-fact 2022-02-02