10% Shareholder Third Rock Ventures Files Intent to Sell Over $17M in Rapport Therapeutics Stock
RAPP has more than doubled off its 52-week low of $7.73 on elevated volume (4.8× avg).
Summary
A major 10% institutional shareholder, Third Rock Ventures, has filed a Form 144 to sell approximately $17.18 million worth of Rapport Therapeutics shares, indicating a potential significant reduction in their holdings.
Key Events · Ownership and Investor Activity · RAPP
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Major Shareholder Intent to Sell
Third Rock Ventures V, L.P., a 10% stockholder, filed a Form 144 to sell 426,005 shares of common stock.
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Significant Value
The proposed sale has an approximate market value of $17.18 million.
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Potential Market Overhang
This filing indicates a substantial block of shares may be sold, potentially adding selling pressure to the stock.
Analysis · RAPP · Life Sciences
Third Rock Ventures V, L.P., a 10% stockholder, has filed a Form 144 indicating its intent to sell 426,005 shares of Rapport Therapeutics common stock, valued at approximately $17.18 million. This proposed sale represents a significant disposition by a major institutional investor, potentially signaling a rebalancing of their portfolio or a strategic reduction in their stake. While not an immediate sale, the filing creates an overhang on the stock as it indicates a substantial block of shares may enter the market. This follows a pattern of insider distribution observed over the last 90 days.
How filings like this one have moved
In the 30 days to Oct 1, 2026, 30.2% of the 1644 measured filings Wiseek scored 7 moved their stock by 5% or more by the next session's close. The median move was -0.49%. These are measured outcomes after filings of this importance, not a forecast for this one.
Measured one observation per ticker per day, after exclusions. Current figures: Filing Impact Tracker · open dataset
At the time of this filing, RAPP was trading at $39.71 on NASDAQ in the Life Sciences sector, with a market capitalization of approximately $1.9B. The 52-week trading range was $7.73 to $42.27. This filing was assessed with negative market sentiment and an importance score of 7 out of 10.