0001950047-23-001294.txt : 20230605 0001950047-23-001294.hdr.sgml : 20230605 20230605164923 ACCESSION NUMBER: 0001950047-23-001294 CONFORMED SUBMISSION TYPE: 144 PUBLIC DOCUMENT COUNT: 1 FILED AS OF DATE: 20230605 DATE AS OF CHANGE: 20230605 SUBJECT COMPANY: COMPANY DATA: COMPANY CONFORMED NAME: Day One Biopharmaceuticals, Inc. CENTRAL INDEX KEY: 0001845337 STANDARD INDUSTRIAL CLASSIFICATION: PHARMACEUTICAL PREPARATIONS [2834] IRS NUMBER: 832415215 STATE OF INCORPORATION: DE FISCAL YEAR END: 1231 FILING VALUES: FORM TYPE: 144 SEC ACT: 1933 Act SEC FILE NUMBER: 001-40431 FILM NUMBER: 23993296 BUSINESS ADDRESS: STREET 1: 2000 SIERRA POINT PARKWAY, SUITE 501 CITY: BRISBANE STATE: CA ZIP: 94005 BUSINESS PHONE: 650 484-0899 MAIL ADDRESS: STREET 1: 2000 SIERRA POINT PARKWAY, SUITE 501 CITY: BRISBANE STATE: CA ZIP: 94005 FORMER COMPANY: FORMER CONFORMED NAME: Day One Biopharmaceuticals Holding Co LLC DATE OF NAME CHANGE: 20210209 REPORTING-OWNER: COMPANY DATA: COMPANY CONFORMED NAME: Blackman Samuel C. CENTRAL INDEX KEY: 0001863676 FILING VALUES: FORM TYPE: 144 MAIL ADDRESS: STREET 1: 395 OYSTER POINT BLVD. STREET 2: SUITE 217 CITY: SOUTH SAN FRANCISCO STATE: CA ZIP: 94080 144 1 primary_doc.xml 144 0001863676 XXXXXXXX LIVE 0001845337 DAY ONE BIOPHARMACEUTICALS INC 001-40431 395 Oyster Point Blvd, Suite 217 Souths San Francisco CA 94080 6504840899 SAMUEL BLACKMAN Officer COMMON Morgan Stanley Smith Barney LLC Executive Financial Services

1 New York Plaza 38th Fl. New York NY 10004

10000 136000.00 73572633 06/05/2023 NASDAQ Common 05/31/2021 Restricted Stock Units Issuer N 10000 05/31/2021 N/A N 10b5-1 Sales Plan for SAMUEL BLACKMAN

395 Oyster Point Blvd, Suite 217 Souths San Francisco CA 94080

Common 03/10/2023 10000 180484.00 06/05/2023 08/23/2022 /s/ Samuel Blackman