X0206 3 2020-10-08 0 0001741830 Kronos Bio, Inc. KRON 0001296549 Belldegrun Arie C/O KRONOS BIO, INC. 1300 SO. EL CAMINO REAL, SUITE 300 SAN MATEO CA 94402 1 0 1 0 Common Stock 255837 I By Bellco Legacy II Trust Series Seed Preferred Stock Common Stock 685750 I By Vida Ventures, LLC Series A Preferred Stock Common Stock 1376313 I By Vida Ventures, LLC Convertible Promissory Note 16.15 2022-02-20 Common Stock 253251 I By Vida Ventures, LLC Series Seed Preferred Stock Common Stock 182866 I By Bellco Legacy II Trust Series A Preferred Stock Common Stock 240872 I By Bellco Legacy II Trust The reporting person currently serves as the trustee of Bellco Legacy II Trust ("Bellco"). His wife, Dr. Rebecka Belldegrun, is the beneficiary of Bellco. Each share of Series Seed Preferred Stock and Series A Preferred Stock (the "Preferred Stock") is convertible into 1.055 shares of Common Stock. The Preferred Stock has no expiration date. VV Manager LLC is the manager of Vida Ventures, LLC ("Vida"). The reporting person is a Senior Managing Director of VV Manager LLC and may therefore be deemed to be the beneficial owner of the securities held by Vida. The reporting person disclaims beneficial ownership of such shares, except to the extent of any pecuniary interest therein. The convertible promissory note will automatically convert into shares of the Issuer's common stock upon the closing of the Issuer's first firm commitment underwritten initial public offering. /s/ David Tanen, Attorney-in-fact 2020-10-08