SCHEDULE: RA Capital Management Files Schedule 13G for Karyopharm Therapeutics

RA Capital Management, L.P., Peter Kolchinsky, Rajeev Shah, and RA Capital Healthcare Fund, L.P. have filed a joint Schedule 13G, indicating a beneficial ownership of 9.99% of Karyopharm Therapeutics Inc. common stock.

Summary

• RA Capital Management, L.P., Peter Kolchinsky, Rajeev Shah, and RA Capital Healthcare Fund, L.P. (collectively, the 'Filers') have entered into a Joint Filing Agreement dated April 2, 2026.
• This agreement allows them to file a single Schedule 13G or 13D with the SEC regarding their beneficial ownership of Karyopharm Therapeutics Inc. common stock.
• The filing indicates a beneficial ownership of 2,078,913 shares of common stock, representing 9.99% of the class.
• This ownership is subject to 'Beneficial Ownership Blockers' in certain warrants held by RA Capital Healthcare Fund, L.P., which limit exercise to prevent ownership exceeding 9.99%.

Sentiment

Score: 5

Explanation: StockSavvy.ai views this as a neutral filing, as it is a standard disclosure of beneficial ownership and does not contain operational or financial performance updates.

Positives

• The joint filing agreement streamlines reporting for multiple entities with shared interests.
• The reporting persons have clearly defined their beneficial ownership and the limitations thereof.

Negatives

• The 'Beneficial Ownership Blockers' in the warrants restrict the full exercise of potential ownership, capping it at 9.99%.

Risks

• The 'Beneficial Ownership Blockers' in the warrants limit the ability to increase ownership beyond 9.99% without triggering restrictions.
• The disclaimer of beneficial ownership for certain purposes by RA Capital, Dr. Kolchinsky, and Mr. Shah, while standard for Section 13(d) obligations, could lead to interpretation complexities in other contexts.

Future Outlook

The filing does not contain forward-looking statements or guidance. It is a disclosure of beneficial ownership.

Management Comments

• The Reporting Persons expressly disclaim status as a 'group' for purposes of this Schedule 13G.
• The Fund has delegated to RA Capital the sole power to vote and the sole power to dispose of all securities held in the Fund's portfolio, including the shares of the Issuer's common stock reported herein.
• 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.
• As managers of RA Capital, Dr. Kolchinsky and Mr. Shah may be deemed beneficial owners, for purposes of Section 13(d) of the Act, of any securities of the Issuer beneficially owned by RA Capital.
• 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.

Industry Context

StockSavvy.ai notes that this filing is a routine Schedule 13G disclosure, indicating a significant but capped ownership stake by RA Capital and its affiliates in Karyopharm Therapeutics. Such filings are common for institutional investors managing large portfolios and often precede or follow strategic investments or market activity.

Stakeholder Impact

• Shareholders: The filing clarifies the ownership structure and potential influence of RA Capital and its affiliates, which is important for understanding the shareholder base.

Next Steps

• The Joint Filing Agreement can be terminated by any of the Filers upon one week's prior written notice or a shorter mutually agreed-upon period.

Key Dates

Keywords

Schedule 13G, Karyopharm Therapeutics, RA Capital Management, Beneficial Ownership, SEC Filing, Joint Filing Agreement, Warrants, Peter Kolchinsky, Rajeev Shah