Form 4: Third Rock Ventures Sells 426K Rapport Therapeutics Shares

Third Rock Ventures V, L.P. sold 426,005 shares of Rapport Therapeutics, Inc. (RAPP) at a weighted average price of $40.317.

Summary

• Third Rock Ventures V, L.P. executed the sale of 426,005 shares of Rapport Therapeutics common stock.
• The transaction occurred on April 17, 2026, at a weighted average price of $40.317 per share.
• The sale was conducted pursuant to a Rule 10b5-1 trading plan adopted on November 21, 2025.
• Following the transaction, Third Rock Ventures V, L.P. retains direct ownership of 6,709,228 shares.
• Third Rock Ventures VI, L.P. maintains an indirect holding of 969,218 shares.

Sentiment

Score: 5

Explanation: StockSavvy.ai views this as a neutral event; while insider selling can be perceived negatively, the use of a pre-planned 10b5-1 program suggests this is a routine portfolio management activity rather than a reaction to negative company news.

Positives

• The sale was executed under a pre-established Rule 10b5-1 trading plan, indicating a systematic rather than reactive divestment strategy.

Negatives

• Significant insider divestment of 426,005 shares may signal a reduction in long-term conviction or portfolio rebalancing by a major institutional shareholder.

Risks

• Continued selling pressure from major institutional holders like Third Rock Ventures could negatively impact the stock price in the short term.

Future Outlook

No specific forward-looking guidance regarding company operations was provided; the filing relates strictly to the reporting of insider equity transactions.

Management Comments

• The reporting person undertakes to provide full information regarding the number of shares sold at each separate price within the reported range upon request.

Industry Context

StockSavvy.ai notes that institutional venture capital firms frequently divest shares in biotech companies following lock-up expirations or as part of standard fund lifecycle management, which is common in the life sciences sector.

Comparison to Industry Standards

• The use of a Rule 10b5-1 plan is the industry standard for institutional investors to avoid allegations of insider trading while liquidating positions.
• Divestment by venture capital firms after a company reaches a certain maturity level is consistent with standard exit strategies for early-stage investors.

Stakeholder Impact

• Shareholders may experience increased volatility due to the volume of shares sold into the market.

Next Steps

• Continued monitoring of Form 4 filings to track further potential divestment by Third Rock Ventures or other major shareholders.

Key Dates

Keywords

Rapport Therapeutics, RAPP, Third Rock Ventures, Insider Trading, Form 4, Biotech, Equity Divestment