X0306 4 2022-12-12 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 2022-12-12 4 M 0 18211 0.67 A 133825 D Common Stock 2022-12-12 4 M 0 8652 4.22 A 142477 D Common Stock 2022-12-12 4 S 0 31699 42.30 D 110778 D Common Stock 2022-12-12 4 S 0 13933 43.15 D 96845 D Common Stock 2022-12-12 4 S 0 5383 43.87 D 91462 D Stock Option (Right to Buy) 0.67 2022-12-12 4 M 0 18211 0.00 D 2028-05-08 Common Stock 18211 189491 D Stock Option (Right to Buy) 4.22 2022-12-12 4 M 0 8652 0.00 D 2029-02-13 Common Stock 8652 4326 D The stock option exercises reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan. The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan. Each sale price reported is a weighted average price. 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 $41.74 to $44.06, inclusive. The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $41.74 to $42.71, inclusive. The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $42.76 to $43.75, inclusive. The price reported in Column 4 is a weighted average price. The shares were sold in multiple transactions at prices ranging from $43.76 to $44.06, inclusive. 25% of the shares subject to the stock option vested on the first anniversary of the vesting commencement date, February 26, 2018, and the remaining shares vested in 36 substantially equal monthly installments thereafter. The option award vests 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. By: /s/ Christine Bellon, Attorney-in-fact 2022-12-14