X0407 4 2023-04-03 0 0001745999 Beam Therapeutics Inc. BEAM 0001963879 Simon Amy C/O BEAM THERAPEUTICS INC. 238 MAIN STREET CAMBRIDGE MA 02142 0 1 0 0 Chief Medical Officer 1 Common Stock 2023-04-03 4 S 0 4445 30.31 D 80962 D Common Stock 2023-04-04 4 S 0 10493 29.7664 D 70469 D Common Stock 2023-04-04 4 S 0 1161 29.0926 D 69308 D The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person prior to February 27, 2023. Includes 278 shares acquired by the Reporting Person under the Beam Therapeutics Inc. Amended and Restated 2019 Employee Stock Purchase Plan on March 31, 2023. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $29.505 to $30.28, inclusive. 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 $28.77 to $29.10, inclusive. The Reporting Person undertakes to provide to 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. By: /s/ Christine Bellon, Attorney-in-fact 2023-04-05