SCHEDULE 13G/A 0001072613-21-000065 0001666306 XXXXXXXX LIVE 3 Common Stock par value $0.01 per share 12/31/2024 0001745999 Beam Therapeutics Inc. 07373V105 238 Main Street Cambridge MA 02142 Rule 13d-1(d) ARCH Venture Fund IX, L.P. DE 0.00 4540132.00 0.00 4540132.00 4540132.00 N 5.5 PN ARCH Venture Fund IX Overage, L.P. DE 0.00 4540132.00 0.00 4540132.00 4540132.00 N 5.5 PN ARCH Venture Partners IX, L.P. DE 0.00 4540132.00 0.00 4540132.00 4540132.00 N 5.5 PN ARCH Venture Partners IX Overage, L.P. DE 0.00 4540132.00 0.00 4540132.00 4540132.00 N 5.5 PN ARCH Venture Partners IX, LLC DE 0.00 4540132.00 0.00 4540132.00 4540132.00 N 5.5 OO Keith Crandell X1 17730.00 4540132.00 17730.00 4540132.00 4557862.00 N 5.5 IN Clinton Bybee X1 10498.00 4540132.00 10498.00 4540132.00 4550630.00 N 5.5 IN Robert Nelsen X1 60615.00 4540132.00 60615.00 4540132.00 4600747.00 N 5.6 IN Beam Therapeutics Inc. 238 Main Street, Cambridge, MA 02142 ARCH Venture Fund IX, L.P. ("AVF IX"); ARCH Venture Partners IX, L.P. ("AVP IX LP"); ARCH Venture Partners IX, LLC ("AVP IX LLC"); ARCH Venture Fund IX Overage, L.P. ("AVF IX Overage"); ARCH Venture Partners IX Overage, L.P. ("AVP IX Overage GP") (collectively, the "Reporting Entities" and individually, each a "Reporting Entity"); and Keith Crandell ("Crandell"), Robert Nelsen ("Nelsen") and Clinton Bybee ("Bybee") (collectively, the "Managing Directors" and individually, each a "Managing Director"). The Reporting Entities and the Managing Directors collectively are referred to as the "Reporting Persons". 8755 W. Higgins Avenue, Suite 1025, Chicago, IL 60631 Each of AVF IX, AVP IX LP, AVF IX Overage and AVP IX Overage GP, are limited partnerships organized under the laws of the State of Delaware. AVP IX LLC is a limited liability company organized under the laws of the State of Delaware. Each Managing Director is a US citizen. Y AVF IX is the record owner of 2,270,067 shares of Common Stock (the "AVF IX Shares") as of December 31, 2024. AVP IX LP, as the sole general partner of AVF IX, may be deemed to beneficially own the AVF IX Shares. AVF IX Overage is the record owner of 2,270,065 shares of Common Stock (the "AVF IX Overage Shares"; combined with the AVF IX Shares, the "Record Shares") as of December 31, 2024. AVP IX Overage GP, as the sole general partner of AVF IX Overage, may be deemed to beneficially own the AVF IX Overage Shares. AVP IX LLC, as the sole general partner of AVP IX LP and AVP IX Overage GP, may be deemed to beneficially own the Record Shares. As managing directors of AVP IX LLC, each Managing Director may also be deemed to share the power to direct the disposition and vote of the Record Shares. In addition, as of December 31, 2024, Crandell is a holder of 17,730 Shares of Common Stock, Bybee and his related trusts are the holder of 10,498 shares of Common Stock, and Nelsen and his related trusts are the holder of 60,615 shares of Common Stock. See line 11 of the cover sheets. The percentages set forth on the cover sheet for each Reporting Person is based upon 82,805,627 shares of common stock outstanding as of October 29, 2024, as reported on the Issuer's Form 10-Q as filed with the Securities and Exchange Commission on November 5, 2024. See line 5 of the cover sheets. See line 6 of the cover sheets. See line 7 of the cover sheets. See line 8 of the cover sheets. Y Y Y Y Y Y ARCH Venture Fund IX, L.P. ARCH Venture Partners IX, L.P. 02/14/2025 ARCH Venture Partners IX, LLC 02/14/2025 /s/ Mark McDonnell 02/14/2025 ARCH Venture Fund IX Overage, L.P. ARCH Venture Partners IX Overage, L.P. 02/14/2025 ARCH Venture Partners IX, LLC 02/14/2025 /s/ Mark McDonnell 02/14/2025 ARCH Venture Partners IX, L.P. ARCH Venture Partners IX, LLC 02/14/2025 /s/ Mark McDonnell 02/14/2025 ARCH Venture Partners IX Overage, L.P. ARCH Venture Partners IX, LLC 02/14/2025 /s/ Mark McDonnell 02/14/2025 ARCH Venture Partners IX, LLC /s/ Mark McDonnell 02/14/2025 Keith Crandell /s/ Mark McDonnell 02/14/2025 Clinton Bybee /s/ Mark McDonnell 02/14/2025 Robert Nelsen /s/ Mark McDonnell 02/14/2025 * This Schedule 13G was executed by Mark McDonnell pursuant to a Power of Attorney filed as Exhibit 24 to the Form 3 relating to the beneficial ownership of shares of Beam Therapeutics, Inc. by the Reporting Persons filed with the Securities Exchange Commission on February 5, 2020 and incorporated herein in its entirety by reference.