Welcome to our dedicated page for Sutro Biopharma SEC filings (Ticker: STRO), a comprehensive resource for investors and traders seeking official regulatory documents including 10-K annual reports, 10-Q quarterly earnings, 8-K material events, and insider trading forms.
Sutro Biopharma filings document the regulatory record of a clinical-stage oncology biotechnology company developing site-specific antibody-drug conjugates. Its SEC disclosures cover operating and financial results, research and development priorities, clinical and regulatory updates for ADC programs, collaboration-related matters, risk factors, and capital-structure activity involving its common stock.
The company’s filings also include definitive proxy materials on shareholder voting, board matters, executive compensation and equity awards. Form 8-K reports document material events such as agreement terminations, restructuring costs, Nasdaq listing-rule notices and compliance updates, and other corporate actions affecting governance, reporting status and financing flexibility.
Barbara Leyman, Chief Business Officer of Sutro Biopharma, reported changes in her holdings on Form 4. She received 25,000 restricted stock units (RSUs) on 07/08/2025 that vest in four equal annual installments beginning 07/08/2025, and those RSUs convert to common stock upon settlement. Following the reported transactions, she beneficially owns 75,000 RSUs. Separately, 8,944 shares of common stock were withheld by the issuer to satisfy tax withholding related to a net settlement of RSUs; this withholding is not a sale by the reporting person. After the withholding and the reported acquisition, she directly beneficially owns 16,056 shares of common stock.
Jane Chung, Chief Executive Officer and Director of Sutro Biopharma, Inc. (STRO), reported insider activity on Form 4 dated 08/26/2025 covering transactions with an earliest date of 08/09/2025. The filing shows the vesting of 18,750 restricted stock units (RSUs) that settled into 18,750 shares of common stock (transaction code M), increasing her beneficial ownership to 117,058 shares. The issuer withheld 6,708 shares
The filers RA Capital Management, L.P., RA Capital Healthcare Fund, L.P., and individuals Peter Kolchinsky and Rajeev Shah submitted an amendment to Schedule 13G for Sutro Biopharma, Inc. (CUSIP 869367102) reporting ownership information as of June 30, 2025. The filing states that each reporting person beneficially owns 0.00 shares and holds 0.0% of the class. The filers expressly disclaim being a group and identify their principal business address as c/o RA Capital Management, L.P., 200 Berkeley Street, 18th Floor, Boston, MA 02116. The filing includes a joint filing agreement incorporated by reference.
Suvretta Capital Management, Averill Master Fund and Aaron Cowen filed an amended Schedule 13G reporting shared beneficial ownership of Sutro Biopharma common stock equal to approximately 6.49 million shares for Suvretta/Cowen and 6.46 million shares for Averill, each representing 7.7% of the class. The filing shows no sole voting or dispositive power and instead reports shared voting and dispositive power for the reported shares. The filing states these securities are directly owned by advisory clients of Suvretta and that, other than Averill, no advisory client is deemed to beneficially own more than 5% of the class. The reporting persons disclaim beneficial ownership except for pecuniary interests and certify the holdings were not acquired to change or influence control of the issuer.