X0306 4 2021-04-29 0 0001564406 Oak Street Health, Inc. OSH 0001793397 COOK TIMOTHY M C/O OAK STREET HEALTH, INC. 30 W. MONROE STREET, SUITE 1200 CHICAGO IL 60603 0 1 0 0 Chief Financial Officer Common stock, $0.001 par value 2021-04-29 4 S 0 7500 61.54 D 1417894 D Common stock, $0.001 par value 2021-04-29 4 S 0 15000 61.54 D 1402894 D Common stock, $0.001 par value 42241 I Through Elizabeth Violet Cook Irrevocable Trust dtd 8/4/2020 Common stock, $0.001 par value 42241 I Through Conner Thomas Cook Irrevocable Trust dtd 8/4/2020 The sales reported in this Form 4 were effected pursuant to a Rule 10b5-1 trading plan previously adopted by the Reporting Person. The Reporting Person undertakes to provide to Oak Street Health, Inc., any security holder of Oak Street Health, Inc., or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each price within the ranges set forth in footnotes (2) through (5) to this Form 4. /s/ Robert Guenthner, as attorney-in-fact for Timothy M. Cook 2021-05-03