SCHEDULE: RA Capital Discloses 9.5% Stake in Assembly Bio

RA Capital Management and its affiliates have disclosed a 9.5% beneficial ownership stake in Assembly Biosciences, Inc., including common stock and warrants.

Summary

• RA Capital Management, L.P., Peter Kolchinsky, Rajeev Shah, and RA Capital Healthcare Fund, L.P. (the "Reporting Persons") have filed a Schedule 13G.
• The Reporting Persons collectively beneficially own 1,530,615 shares of Assembly Biosciences, Inc. common stock.
• This ownership represents 9.5% of the outstanding common stock of Assembly Biosciences, Inc.
• The ownership includes 1,020,410 shares of common stock directly held by RA Capital Healthcare Fund, L.P.
• It also includes Class A Warrants exercisable for up to 510,205 shares, which are immediately exercisable.
• Additionally, Class B Warrants exercisable for up to 510,205 shares are included, becoming exercisable on or after November 15, 2026, and expiring on December 31, 2026.
• The percentage is calculated based on 15,560,009 shares outstanding as of August 11, 2025, plus the 510,205 shares issuable from Class A Warrants.
• A beneficial ownership blocker prevents exercise of warrants if it would result in ownership exceeding 9.99%.

Sentiment

Score: 6

Explanation: The filing is a standard Schedule 13G disclosing a significant beneficial ownership stake by a specialized investment firm, RA Capital Management, in Assembly Biosciences, Inc. While it doesn't contain operational news, the substantial stake (9.5%) by a reputable healthcare investor can be viewed as a positive signal of confidence in the company's long-term prospects. The terms of the Class B Warrants also hint at a potential future capital raise.

Positives

• A significant institutional investor, RA Capital Management, has taken a substantial 9.5% stake, potentially signaling confidence in Assembly Biosciences' long-term prospects.
• The investment includes warrants, indicating a potential for increased ownership by RA Capital if certain conditions are met or if the investor chooses to exercise.

Negatives

• The Class B Warrants have a termination clause tied to a non-dilutive capital raise of at least $75.0 million prior to November 15, 2026, which could limit future upside from these specific warrants for the holder if the company successfully raises capital.

Risks

• The Class B Warrants will automatically terminate if Assembly Biosciences, Inc. completes a non-dilutive capital raise of at least $75.0 million prior to November 15, 2026, potentially reducing RA Capital's future ownership percentage from these specific warrants.
• The Beneficial Ownership Blocker limits the exercise of warrants if it would cause the Fund's ownership to exceed 9.99% of outstanding common stock, restricting potential full exercise.

Future Outlook

The filing, primarily a disclosure of current ownership, indicates that Assembly Biosciences, Inc. may pursue a non-dilutive capital raise of at least $75.0 million prior to November 15, 2026, as this event would trigger the automatic termination of the Class B Warrants held by RA Capital Healthcare Fund, L.P.

Industry Context

RA Capital Management is a prominent healthcare and life sciences investment firm. Their investment in Assembly Biosciences, a biotechnology company, aligns with their specialization in the sector. Such an investment by a specialized fund can be seen as a vote of confidence in the company's pipeline or strategic direction within the competitive biotech landscape.

Related Party Transactions

• RA Capital Management, L.P. serves as the investment adviser for RA Capital Healthcare Fund, L.P. and has been delegated sole power to vote and dispose of securities held by the Fund.
• RA Capital Management GP, LLC is the general partner of RA Capital, and Peter Kolchinsky and Rajeev Shah are its controlling persons.
• RA Capital Healthcare Fund GP, LLC is the general partner of RA Capital Healthcare Fund, L.P.
• Peter Kolchinsky and Rajeev Shah are deemed beneficial owners due to their control over RA Capital.

Stakeholder Impact

• Shareholders: The disclosure of a significant institutional stake by RA Capital could be viewed positively, potentially increasing investor confidence and attracting further institutional interest. The terms of the warrants, particularly the Class B warrants, could impact future dilution depending on their exercise or termination.
• Company Management: Awareness of a significant institutional holder like RA Capital may influence strategic decisions, particularly regarding capital raises and clinical milestones.

Next Steps

• Class A Warrants will expire upon the earlier of five years from issuance or 30 days after a public announcement of a predefined clinical milestone.
• Class B Warrants become exercisable on or after November 15, 2026, and expire on December 31, 2026.
• Assembly Biosciences, Inc. may pursue a non-dilutive capital raise of at least $75.0 million prior to November 15, 2026, which would terminate the Class B Warrants.

Key Dates

Keywords

Assembly Biosciences, RA Capital Management, Peter Kolchinsky, Rajeev Shah, Schedule 13G, beneficial ownership, common stock, warrants, institutional investment, biotechnology, pharmaceutical