X0306 4 2023-01-03 0 0001745999 Beam Therapeutics Inc. BEAM 0001786322 Ciaramella Giuseppe C/O BEAM THERAPEUTICS INC., 238 MAIN STREET CAMBRIDGE MA 02142 0 1 0 0 President & CSO Common Stock 2023-01-03 4 M 0 9106 0.67 A 105068 D Common Stock 2023-01-03 4 M 0 4326 4.22 A 109394 D Common Stock 2023-01-03 4 M 0 40297 0.67 A 149691 D Common Stock 2023-01-03 4 S 0 37525 37.14 D 112166 D Common Stock 2023-01-03 4 S 0 13704 37.99 D 98462 D Common Stock 2023-01-03 4 S 0 1900 39.07 D 96562 D Common Stock 2023-01-03 4 S 0 600 39.94 D 95962 D Stock Option (Right to Buy) 0.67 2023-01-03 4 M 0 9106 0.00 D 2028-05-08 Common Stock 9106 0 D Stock Option (Right to Buy) 4.22 2023-01-03 4 M 0 4326 0.00 D 2029-02-13 Common Stock 4326 0 D Stock Option (Right to Buy) 0.67 2023-01-03 4 M 0 40297 0.00 D 2028-05-08 Common Stock 40297 150905 D The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan. The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $36.66 to $37.65, inclusive. The Reporting Person undertakes to provide 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. The shares were sold in multiple transactions at prices ranging from $37.66 to $38.48, inclusive. The Reporting Person undertakes to provide 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. The shares were sold in multiple transactions at prices ranging from $38.82 to $39.75, inclusive. The Reporting Person undertakes to provide 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 option award vested upon the achievement of a closing price hurdle following BEAM's initial public offering (which closing price hurdle has been achieved) in three equal installments on December 21, 2021, June 30, 2022 and December 31, 2022. The shares subject to this stock option vested 25% on the first anniversary of the vesting commencement date, February 26, 2018, and the remaining shares vested in 36 substantially equal monthly installments thereafter. By: /s/ Christine Bellon, Attorney-in-fact 2023-01-05