BEAM · Beam Therapeutics Inc.

The transactions reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on March 27, 2026.

The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $25.32 to $26.05, 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 stock options were exercised and the shares of common stock were sold pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on May 16, 2025.

On July 13, 2018, the Reporting Person was granted an option to purchase 539,645 shares of common stock, which vested as to 25% of the underlying shares on January 8, 2019 and in 36 equal monthly installments thereafter.

The stock options were exercised and the shares of common stock were sold pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on May 16, 2025.

The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $34.83 to $34.85, 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.

The stock options were exercised and the shares of common stock were sold pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on May 16, 2025.

These shares of common stock were automatically sold in a non-discretionary transaction by the Reporting Person in order to cover tax withholding obligations upon the vesting of certain restricted stock units granted to the Reporting Person under the Beam Therapeutics Inc. ("BEAM") 2019 Equity Incentive Plan on June 30, 2022. The sales were effected pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on May 19, 2023.

The stock options were exercised and the shares of common stock were sold pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on May 16, 2025.

The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $33.80 to $34.71, 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.

The stock options were exercised and the shares of common stock were sold pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on May 16, 2025.

The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $35.60 to $36.18, 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.

The stock options were exercised and the shares of common stock were sold pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on May 16, 2025.

The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $34.55 to $35.50, 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 stock options were exercised and the shares of common stock were sold pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on May 16, 2025.

The stock options were exercised and the shares of common stock were sold pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on May 16, 2025.

The stock options were exercised and the shares of common stock were sold pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on May 16, 2025.

On May 8, 2018, the Reporting Person was granted an option to purchase shares of common stock, which vested as to 99,396 shares upon the achievement of a certain development milestone related to base editing applications. On April 3, 2024, the board of directors of BEAM determined that this performance condition was achieved, resulting in the vesting of 99,336 shares.

The stock options were exercised and the shares of common stock were sold pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on May 16, 2025.

On July 13, 2018, the Reporting Person was granted an option to purchase 539,645 shares of common stock, which vested as to 25% of the underlying shares on January 8, 2019 and in 36 equal monthly installments thereafter.

The price reported for this transaction is the weighted average price of multiple trades at prices ranging from $35.00 to $35.88. FMR LLC hereby undertakes to provide upon request by the Commission staff, the issuer, or a security holder of the issuer full information.

The price reported for this transaction is the weighted average price of multiple trades at prices ranging from $35.00 to $35.39. FMR LLC hereby undertakes to provide upon request by the Commission staff, the issuer, or a security holder of the issuer full information.

The shares subject to these stock options vested 25% on the first anniversary of the vesting commencement dates, February 26, 2018, and the remaining shares vested in 36 substantially equal monthly installments thereafter.

The shares subject to these stock options vested 25% on the first anniversary of the vesting commencement dates, February 26, 2018, and the remaining shares vested in 36 substantially equal monthly installments thereafter.

The option vests in full on the earlier of the first anniversary of the date of grant and immediately prior to the date of the next year's annual meeting of stockholders, subject to the reporting person's continued service to the board of directors of Beam Therapeutics Inc. through the vesting date.

The option vests in full on the earlier of the first anniversary of the date of grant and immediately prior to the date of the next year's annual meeting of stockholders, subject to the reporting person's continued service to the board of directors of Beam Therapeutics Inc. through the vesting date.

The option vests in full on the earlier of the first anniversary of the date of grant and immediately prior to the date of the next year's annual meeting of stockholders, subject to the reporting person's continued service to the board of directors of Beam Therapeutics Inc. through the vesting date.

The option vests in full on the earlier of the first anniversary of the date of grant and immediately prior to the date of the next year's annual meeting of stockholders, subject to the reporting person's continued service to the board of directors of Beam Therapeutics Inc. through the vesting date.

The option vests in full on the earlier of the first anniversary of the date of grant and immediately prior to the date of the next year's annual meeting of stockholders, subject to the reporting person's continued service to the board of directors of Beam Therapeutics Inc. through the vesting date.

The option vests in full on the earlier of the first anniversary of the date of grant and immediately prior to the date of the next year's annual meeting of stockholders, subject to the reporting person's continued service to the board of directors of Beam Therapeutics Inc. through the vesting date.

These shares of common stock were automatically sold in a non-discretionary transaction by the Reporting Person in order to cover tax withholding obligations upon the vesting of certain restricted stock units granted to the Reporting Person under the Beam Therapeutics Inc. 2019 Equity Incentive Plan on each of March 31, 2022, March 31, 2023, March 31, 2024 and March 31, 2025. The sales were effected pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on May 19, 2023.

These shares of common stock were automatically sold in a non-discretionary transaction by the Reporting Person in order to cover tax withholding obligations upon the vesting of certain restricted stock units granted to the Reporting Person under the Beam Therapeutics Inc. ("BEAM") 2019 Equity Incentive Plan on each of March 31, 2022, March 31, 2023, March 31, 2024 and March 31, 2025. The sales were effected pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on May 19, 2023.

Includes 616 shares acquired by the Reporting Person under the BEAM Amended and Restated 2019 Employee Stock Purchase Plan on March 31, 2026.

These shares of common stock were automatically sold in a non-discretionary transaction by the Reporting Person in order to cover tax withholding obligations upon the vesting of certain restricted stock units granted to the Reporting Person under the Beam Therapeutics Inc. 2019 Equity Incentive Plan on each of March 31, 2022, March 31, 2023, March 31, 2024 and March 31, 2025. The sales were effected pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on May 23, 2023.

These shares of common stock were automatically sold in a non-discretionary transaction by the Reporting Person in order to cover tax withholding obligations upon the vesting of certain restricted stock units granted to the Reporting Person under the Beam Therapeutics Inc. 2019 Equity Incentive Plan on each of March 31, 2022, March 31, 2023, March 31, 2024 and March 31, 2025. The sales were effected pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on August 9, 2024.

These shares of common stock were automatically sold in a non-discretionary transaction by the Reporting Person in order to cover tax withholding obligations upon the vesting of certain restricted stock units granted to the Reporting Person under the Beam Therapeutics Inc. ("BEAM") 2019 Equity Incentive Plan on each of March 31, 2022, March 31, 2023, March 31, 2024 and March 31, 2025. The sales were effected pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on May 19, 2023.

Includes 183 and 138 shares acquired by the Reporting Person under the BEAM Amended and Restated 2019 Employee Stock Purchase Plan on September 30, 2025 and March 31, 2026, respectively.

Represents restricted stock units ("RSUs") granted to the Reporting Person under the Beam Therapeutics Inc. ("BEAM") 2019 Equity Incentive Plan. Each RSU represents the contingent right to receive one share of BEAM's common stock. The RSUs vest in four substantially equal installments on each of the first four anniversaries of the date of grant, subject to the Reporting Person's continued service with BEAM through each vesting date.

Represents restricted stock units ("RSUs") granted to the Reporting Person under the Beam Therapeutics Inc. ("BEAM") 2019 Equity Incentive Plan. Each RSU represents the contingent right to receive one share of BEAM's common stock. The RSUs vest in four substantially equal installments on each of the first four anniversaries of the date of grant, subject to the Reporting Person's continued service with BEAM through each vesting date.

Represents restricted stock units ("RSUs") granted to the Reporting Person under the Beam Therapeutics Inc. ("BEAM") 2019 Equity Incentive Plan. Each RSU represents the contingent right to receive one share of BEAM's common stock. The RSUs vest in four substantially equal installments on each of the first four anniversaries of the date of grant, subject to the Reporting Person's continued service with BEAM through each vesting date.

Represents restricted stock units ("RSUs") granted to the Reporting Person under the Beam Therapeutics Inc. ("BEAM") 2019 Equity Incentive Plan. Each RSU represents the contingent right to receive one share of BEAM's common stock. The RSUs vest in four substantially equal installments on each of the first four anniversaries of the date of grant, subject to the Reporting Person's continued service with BEAM through each vesting date.

These shares of common stock were sold pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on May 16, 2025.

On May 8, 2018, the Reporting Person was granted an option to purchase shares of common stock, which vested as to 99,396 shares upon the achievement of a certain development milestone related to base editing applications. On April 3, 2024, the board of directors of BEAM determined that this performance condition was achieved, resulting in the vesting of 99,336 shares.

Represents restricted stock units ("RSUs") granted to the Reporting Person under the Beam Therapeutics Inc. ("BEAM") 2019 Equity Incentive Plan. Each RSU represents the contingent right to receive one share of BEAM's common stock. The RSUs vest in four substantially equal installments on each of the first four anniversaries of the date of grant, subject to the Reporting Person's continued service with BEAM through each vesting date.

These shares of common stock were sold pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on May 16, 2025.

The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $22.34 to $23.21, 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.

These shares of common stock were sold pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on May 16, 2025.

Represents restricted stock units ("RSUs") granted to the Reporting Person under the BEAM 2019 Equity Incentive Plan. Each RSU represents the contingent right to receive one share of BEAM's common stock. The RSUs vest in four substantially equal installments on each of the first four anniversaries of the date of grant, subject to the Reporting Person's continued service with BEAM through each vesting date.

These shares of common stock were sold pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on May 16, 2025.

The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $22.03 to $22.70, 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.

These shares of common stock were sold pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on May 16, 2025.

These shares of common stock were sold pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on May 16, 2025.

On May 8, 2018, the Reporting Person was granted an option to purchase shares of common stock, which vested as to 99,396 shares upon the achievement of a certain development milestone related to base editing applications. On April 3, 2024, the board of directors of BEAM determined that this performance condition was achieved, resulting in the vesting of 99,336 shares.

The option vests as to 25% on the first anniversary of the of the vesting commencement date, February 5, 2020, and at a rate of 2.78% each month thereafter until the option is fully vested.

The shares of Common Stock were sold pursuant to a Rule 10b5-1 trading plan adopted by the Reporting Person on September 30, 2025.

The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions ranging from $32.00 to $32.04, 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.

This stock 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 Therapeutics Inc. through each vesting date.

This stock 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 Therapeutics Inc. through each vesting date.

This stock 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.

This stock 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 Therapeutics Inc. through each vesting date.

This stock 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 Therapeutics Inc. through each vesting date.

This stock 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.