AMAM Ambrx Biopharma Inc

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 6-K

REPORT OF FOREIGN ISSUER

PURSUANT TO RULE 13a-16 OR 15d-16

OF THE SECURITIES EXCHANGE ACT OF 1934

August 29, 2022

(Commission File No. 001-40505)

Ambrx Biopharma Inc.

(Translation of registrant’s name into English)

Cayman Islands

(Jurisdiction of incorporation or organization)

10975 Torrey Pines Road

La Jolla, California 92037, United States

(Address of registrant’s principal executive office)

Indicate by check mark whether the registrant files or will file annual reports under cover Form 20-F or Form 40-F.

Form 20-F  ☒             Form 40-F  ☐

Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(1):  ☐

Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(7):  ☐

Earnings Release

On August 29, 2022, Ambrx Biopharma Inc. issued a press release regarding its financial results as of and for the six months ended June 30, 2022 and recent business highlights, which is attached to this Form 6-K as Exhibit 99.1.

This report on Form 6-K is hereby incorporated by reference into the Company’s Registration Statements on Form S-8 (Registration No. 333-257264 and No. 333-264490), and Form F-3 (Registration No. 333-266404).