X0206 3 2020-02-05 0 0001745999 Beam Therapeutics Inc. BEAM 0001219042 NELSEN ROBERT 8755 W. HIGGINS ROAD, SUITE 1025 CHICAGO IL 60631 1 0 1 0 Series A-1 Preferred Stock Common Stock 1338000 I See footnote Series A-1 Preferred Stock Common Stock 1338000 I See footnote Series A-2 Preferred Stock Common Stock 2750336 I See footnote Series A-2 Preferred Stock Common Stock 2750335 I See footnote Series B Preferred Stock Common Stock 33184 I See footnote Series B Preferred Stock Common Stock 33184 I See footnote The shares are held by ARCH Venture Fund IX, L.P. ("ARCH IX"). The Reporting Person is a managing director of ARCH Venture Partners IX, LLC, the sole general partner of ARCH Venture Partners IX, L.P., which is the sole general partner of ARCH IX, and shares voting and investment control with respect to shares held by ARCH IX. The Reporting Person may be deemed to beneficially own the shares held by ARCH IX, and the Reporting Person disclaims ownership of such shares, except to the extent of his pecuniary interest therein. Each share of Series A-1 Convertible Preferred Stock, Series A-2 Convertible Preferred Stock and Series B Convertible Preferred Stock (collectively, the "Preferred Stock") is convertible into shares of common stock at any time at the holder's election and automatically upon the consummation of a qualified public offering of the registrant, for no additional consideration. There is no expiration date for the Preferred Stock. The shares are directly held by ARCH Venture Fund IX Overage, L.P. ("ARCH Overage"). The Reporting Person is a managing director of ARCH Venture Partners IX, LLC, the sole general partner of ARCH Venture Partners IX Overage, L.P. ("Overage GPLP"), which is the sole general partner of ARCH Overage, and shares voting and investment control with respect to shares held by ARCH Overage. The Reporting Person disclaims ownership of such shares, except to the extent of his pecuniary interest therein. Exhibit List: Exhibit 24 - Power of Attorney By: /s/ Christine Bellon, Attorney-in-Fact 2020-02-05