X0306 4 2022-04-28 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 2022-04-28 4 M 0 12246 7.22 A 1101316 D Common Stock 2022-04-28 4 M 0 47204 1.03 A 1148520 D Common Stock 2022-04-28 4 S 0 3900 36.59 D 1144620 D Common Stock 2022-04-28 4 S 0 13655 37.48 D 1130965 D Common Stock 2022-04-28 4 S 0 6842 38.32 D 1124123 D Common Stock 2022-04-28 4 S 0 4503 39.49 D 1119620 D Common Stock 2022-04-28 4 S 0 1100 40.73 D 1118520 D Common Stock 2022-04-28 4 S 0 6450 36.98 D 156550 I By John M. Evans, III 2018 Irrevocable Trust Common Stock 2022-04-28 4 S 0 7745 37.84 D 148805 I By John M. Evans, III 2018 Irrevocable Trust Common Stock 2022-04-28 4 S 0 3100 38.75 D 145705 I By John M. Evans, III 2018 Irrevocable Trust Common Stock 2022-04-28 4 S 0 2348 39.73 D 143357 I By John M. Evans, III 2018 Irrevocable Trust Common Stock 2022-04-28 4 S 0 357 40.88 D 143000 I By John M. Evans, III 2018 Irrevocable Trust Stock Option (Right to Buy) 7.22 2022-04-28 4 M 0 12246 0.00 D 2029-05-17 Common Stock 12246 210754 D Stock Option (Right to Buy) 1.03 2022-04-28 4 M 0 47204 0.00 D 2028-07-13 Common Stock 47204 237141 D 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 $36.36 to $36.97, inclusive. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $37.06 to $37.86, inclusive. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $38.09 to $38.67, inclusive. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $39.21 to $39.88, inclusive. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $40.08 to $40.80, inclusive. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $36.36 to $37.34, inclusive. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $37.38 to $38.37, inclusive. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $38.405 to $39.261, inclusive. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $39.51 to $40.32, inclusive. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $40.70 to $40.96, 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 as to 25% on the first anniversary of the of the vesting commencement date, October 1, 2019, and at a rate of 2.78% each month thereafter until the option is fully vested. By: /s/ Christine Bellon, Attorney-in-fact 2022-05-02