As filed with the Securities and Exchange Commission on February 10, 2021

No. 333-                

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM S-1

REGISTRATION STATEMENT

UNDER

THE SECURITIES ACT OF 1933

Oak Street Health, Inc.

(Exact name of registrant as specified in its charter)

30 W. Monroe Street

Suite 1200

Chicago, Illinois 60603

Telephone: (312) 733-9730

(Address, including zip code, and telephone number, including area code, of registrant’s principal executive offices)

Mike Pykosz

Chief Executive Officer

30 W. Monroe Street

Suite 1200

Chicago, Illinois 60603

Telephone: (312) 733-9730

(Name, address, including zip code, and telephone number, including area code, of agent for service)

Copies of all communications, including communications sent to agent for service, should be sent to:

Approximate date of commencement of proposed sale to the public: As soon as practicable after this Registration Statement becomes effective.

If any of the securities being registered on this Form are to be offered on a delayed or continuous basis pursuant to Rule 415 under the Securities Act of 1933, check the following box:  ☐

If this Form is filed to registered additional securities for an offering pursuant to Rule 462(b) under the Securities Act, please check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering.  ☒ File Number 333-252843

If this Form is a post-effective amendment filed pursuant to Rule 462(c) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering.  ☐

If this Form is a post-effective amendment filed pursuant to Rule 462(d) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering.  ☐

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “smaller reporting company,” and “emerging growth company” in Rule 12b-2 of the Exchange Act.

CALCULATION OF REGISTRATION FEE

This Registration Statement shall become effective upon filing with the Securities and Exchange Commission in accordance with Rule 462(b) promulgated under the Securities Act.

EXPLANATORY NOTE AND INCORPORATION OF

CERTAIN INFORMATION BY REFERENCE

This Registration Statement on Form S-1 is being filed with respect to the registration of additional shares of common stock, par value $0.001 per share, of Oak Street Health, Inc., a Delaware corporation, pursuant to Rule 462(b) under the Securities Act of 1933, as amended. This Registration Statement includes the registration statement facing page, this page, the signature page, an exhibit index, an opinion of counsel regarding the legality of the securities being registered and a related consent and accountants’ consent. This Registration Statement relates to the Registrant’s Registration Statement on Form S-1, as amended (File No. 333-252843), initially filed by the Registrant on February 8, 2021, declared effective by the Securities and Exchange Commission on February 10, 2021. The Registrant is filing this Registration Statement for the sole purpose of increasing the aggregate number of shares of common stock offered by the selling shareholders by 1,982,394 shares, which includes 258,573 additional shares that the underwriters have the option to purchase. Pursuant to Rule 462(b), the contents of the Registration Statement on Form S-1 (File No. 333-252843), including the exhibits and the power of attorney thereto, are incorporated by reference into this Registration Statement.

EXHIBIT INDEX

SIGNATURES

Pursuant to the requirements of the Securities Act of 1933, the registrant has duly caused this Registration Statement to be signed on its behalf by the undersigned, thereunto duly authorized in the City of Chicago, State of Illinois, on February 10, 2021.

Pursuant to the requirements of the Securities Act of 1933, this Registration Statement has been signed by the following persons in the capacities and on the dates indicated.