SEC Form 8-K filed by Sutro Biopharma Inc.

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d)

of the Securities Exchange Act of 1934

Date of Report (Date of earliest event reported): December 17, 2025

SUTRO BIOPHARMA, INC.

(Exact name of registrant as specified in its charter)

111 Oyster Point Blvd,

South San Francisco, California, 94080

(Address of principal executive offices) (Zip Code)

(650) 881-6500

(Registrant’s telephone number, including area code)

Not Applicable

(Former name or former address, if changed since last report)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

Securities registered pursuant to Section 12(b) of the Act:

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§ 230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§ 240.12b-2 of this chapter).

Emerging growth company ☐  

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

Item 8.01 Other Events.

On December 17, 2025, Sutro Biopharma, Inc. (the “Company”) received notice from the Listing Qualifications staff (the “Staff”) of the Nasdaq Stock Market LLC (“Nasdaq”) confirming that the Company has regained compliance with Nasdaq Listing Rule 5450(a)(1). As of December 16, 2025, the closing bid price of the Company’s common stock had been at least $1.00 per share for 10 consecutive business days, and the Company satisfies all other applicable criteria for continued listing on The Nasdaq Global Market. As a result of this determination, the listing matter is now closed.

As previously disclosed, on June 20, 2025, the Company received notice from the Staff of Nasdaq that, because the closing bid price for the Company’s common stock had fallen below $1.00 per share for 30 consecutive business days, the Company no longer complied with the minimum bid price requirement for continued listing on The Nasdaq Global Market under Nasdaq Listing Rule 5450(a)(1).

SIGNATURE

Pursuant to the requirements of the Securities Exchange Act of 1934, as amended, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.