SCHEDULE 13G: RA Capital Management Discloses 5.3% Passive Stake in Sutro Biopharma

RA Capital Management, L.P. and its affiliates have disclosed a passive beneficial ownership of 5.3% of Sutro Biopharma, Inc.'s common stock.

Summary

• RA Capital Management, L.P., Peter Kolchinsky, Rajeev Shah, and RA Capital Healthcare Fund, L.P. (collectively, the "Filers") have filed a Schedule 13G with the SEC.
• The filing reports beneficial ownership of 4,434,637 shares of Sutro Biopharma, Inc. common stock.
• This stake represents 5.3% of Sutro Biopharma's outstanding common stock, calculated based on 83,775,336 shares outstanding as of March 6, 2025.
• The ownership is primarily held by RA Capital Healthcare Fund, L.P., with RA Capital Management, L.P. serving as the investment adviser and holding shared voting and dispositive power over the shares.
• Peter Kolchinsky and Rajeev Shah, as controlling persons of RA Capital Management GP, LLC, are also deemed beneficial owners.
• The Filers have certified that the securities were acquired and are held for passive investment purposes and not with the intent to change or influence the control of Sutro Biopharma.

Sentiment

Score: 6

Explanation: The filing is a standard disclosure of a passive ownership stake. While it doesn't inherently convey strong positive or negative sentiment, the involvement of a reputable healthcare-focused investment firm like RA Capital Management can be viewed as a positive signal of confidence in Sutro Biopharma's long-term prospects, hence a slightly positive score.

Positives

• A significant investment firm, RA Capital Management, has taken a passive stake in Sutro Biopharma, which may signal confidence in the company's long-term prospects.
• The investment is declared as passive, indicating no immediate intent by the reporting persons to influence or change the company's control or management.

Risks

• The Reporting Persons (RA Capital, Dr. Kolchinsky, and Mr. Shah) disclaim beneficial ownership of the securities for any purpose other than determining their obligations under Section 13(d) of the Securities Exchange Act of 1934.
• RA Capital Healthcare Fund, L.P. disclaims beneficial ownership of the securities it holds for purposes of Section 13(d) of the Act, as it has delegated voting and investment power to RA Capital and cannot revoke this delegation on less than 61 days' notice.

Future Outlook

The document is a beneficial ownership disclosure and does not contain forward-looking statements or guidance regarding the issuer's future performance or strategic direction.

Management Comments

• "The Filers hereby agree to file a single statement on Schedule 13G and/or 13D (and any amendments thereto) on behalf of each of such parties."
• "The Reporting Persons expressly disclaim status as a 'group' for purposes of this Schedule 13G."
• "By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect, other than activities solely in connection with a nomination under §§ 240.14a-11."
• "RA Capital, Dr. Kolchinsky, and Mr. Shah disclaim beneficial ownership of the securities reported in this Schedule 13G other than for the purpose of determining their obligations under Section 13(d) of the Act, and the filing of this Schedule 13G shall not be deemed an admission that either RA Capital, Dr. Kolchinsky, or Mr. Shah is the beneficial owner of such securities for any other purpose."
• "Because the Fund has divested voting and investment power over the reported securities it holds and may not revoke that delegation on less than 61 days' notice, the Fund disclaims beneficial ownership of the securities it holds for purposes of Section 13(d) of the Act."

Industry Context

This filing indicates a significant passive investment by a specialized healthcare fund in a biopharmaceutical company, a common occurrence in the biotechnology sector where institutional investors often take positions in promising drug development firms.

Stakeholder Impact

• Shareholders: The disclosure of a significant passive stake by a reputable investment firm may be viewed positively, potentially increasing investor confidence.
• Company Management: Awareness of a significant passive investor on the shareholder register.

Key Dates

Keywords

Sutro Biopharma, RA Capital Management, Schedule 13G, beneficial ownership, common stock, biotechnology, investment fund, passive investment, Peter Kolchinsky, Rajeev Shah