Form 4: RA Capital Adjusts Climb Bio Holdings, Buys Shares

RA Capital Management, a significant shareholder and director at Climb Bio, Inc., reported an exchange of common stock for pre-funded warrants and subsequent purchases of additional common stock.

Summary

• RA Capital Healthcare Fund, L.P. exchanged 20,440,000 shares of Climb Bio common stock for an equal number of pre-funded warrants on December 11, 2025, at an exercise price of $0.0001 per share, with no additional consideration.
• The pre-funded warrants are immediately exercisable and have no expiration date, subject to a 33.0% beneficial ownership cap for the reporting persons and their affiliates.
• RA Capital Healthcare Fund, L.P. purchased 213,099 shares of common stock on December 11, 2025, at a weighted average price of $2.18 per share, with prices ranging from $2.11 to $2.20.
• RA Capital Healthcare Fund, L.P. purchased an additional 101,462 shares of common stock on December 12, 2025, at a weighted average price of $2.86 per share, with prices ranging from $2.32 to $3.00.
• RA Capital Management, L.P. and its affiliated funds (Nexus Fund, Nexus Fund II, Nexus Fund III, and a separately managed account) and Sera Medicines, LLC hold additional indirect beneficial ownership in Climb Bio.
• The transactions were made pursuant to a Rule 10b5-1(c) plan.

Sentiment

Score: 7

Explanation: The filing indicates continued investment and strategic positioning by a major institutional investor, RA Capital, through both direct purchases and the conversion to pre-funded warrants. This suggests confidence in Climb Bio's long-term prospects, despite the technical nature of the warrant exchange.

Positives

• Significant insider purchases totaling 314,561 shares by a major institutional investor (RA Capital) indicate confidence in the company's future prospects.
• The exchange of common stock for pre-funded warrants allows RA Capital to maintain a substantial economic interest while potentially managing its beneficial ownership percentage, especially with the 33.0% cap.
• The pre-funded warrants have a very low exercise price ($0.0001), providing long-term upside potential with minimal additional capital outlay.

Negatives

• The exchange of common stock for warrants, while a strategic move, could be interpreted as a mechanism to manage immediate voting power or regulatory thresholds, rather than a direct increase in capital commitment at the time of exchange.

Risks

• The beneficial ownership limitation on the pre-funded warrants (not to exceed 33.0% of outstanding shares upon exercise) could restrict RA Capital's ability to fully exercise its warrants if the company's share count does not increase sufficiently.

Future Outlook

The filing does not contain specific forward-looking statements or guidance regarding the company's future performance or strategic direction, beyond the nature of the pre-funded warrants having no expiration date.

Management Comments

• RA Capital Management, L.P. (the 'Adviser') is the investment manager for the Fund, RA Capital Nexus Fund, L.P. (the 'Nexus Fund'), RA Capital Nexus II Fund, L.P. (the 'Nexus Fund II'), RA Capital Nexus III Fund, L.P. (the 'Nexus Fund III') and a separately managed account (the 'Account').
• The Adviser, the Adviser GP, the Fund, the Nexus Fund, the Nexus Fund II, the Nexus Fund III, Dr. Kolchinsky and Mr. Shah disclaim beneficial ownership of the reported securities, except to the extent of their respective pecuniary interest therein.
• The Reporting Persons undertake to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares purchased at each separate price within the range set forth in this footnote.

Industry Context

This Form 4 filing reflects an institutional investor's active management of its stake in a biotechnology company. Such transactions are common in the biotech sector where early-stage investments often involve complex equity structures and where investors like RA Capital frequently take board seats to guide strategic development. The purchases suggest continued confidence in Climb Bio's potential, while the warrant exchange could be a strategic move to optimize capital structure or regulatory compliance for a significant shareholder.

Corporate Governance

Related Party Transactions

• RA Capital Management, L.P. acts as investment manager for several funds (RA Capital Healthcare Fund, Nexus Fund, Nexus Fund II, Nexus Fund III) and a separately managed account, all of which hold beneficial ownership in Climb Bio.
• Peter Kolchinsky and Rajeev Shah are managing members of RA Capital Management GP, LLC, the general partner of RA Capital Management, L.P., and are also reporting persons.
• The Fund and Nexus Fund III collectively own approximately 75% of Sera Medicines, LLC, which also holds Climb Bio securities.
• Dr. Andrew Levin, a Partner and Managing Director of RA Capital Management, L.P., serves on Climb Bio's board of directors.

Stakeholder Impact

• Shareholders: The purchases by a significant institutional investor could be viewed positively, signaling confidence. The warrant exchange might dilute future shareholders if exercised, but also provides a mechanism for the investor to maintain exposure.
• Management: The presence of RA Capital representatives on the board (Dr. Andrew Levin) indicates active oversight and strategic input from a major investor.

Key Dates

Recommendation

While the insider purchases by RA Capital Management and its affiliates signal confidence in Climb Bio, the Form 4 filing primarily details transactional activities rather than fundamental business performance. The strategic exchange of common stock for pre-funded warrants, coupled with the beneficial ownership cap, suggests a nuanced approach to maintaining a significant stake. Without additional information on the company's operational performance, financials, or strategic pipeline, a 'hold' recommendation is prudent, acknowledging the positive insider sentiment while awaiting more comprehensive data for a stronger conviction.

Keywords

Climb Bio, CLYM, RA Capital Management, Insider Trading, Form 4, Stock Purchase, Warrants, Pre-Funded Warrants, Biotechnology, Healthcare Investment, Institutional Investor, Beneficial Ownership