Third Rock Ventures V, L.P. 4

What Happened

• Third Rock Ventures V, L.P. (a reported 10% owner of Rapport Therapeutics, ticker RAPP) sold 426,005 shares on April 17, 2026. The sales were effected at a weighted-average price of $40.32 per share for total proceeds of $17,175,244. This was a sale (not a purchase) and therefore generally a liquidity event rather than an indicated vote of confidence in the company.

Key Details

• Transaction date and prices: April 17, 2026; shares sold in multiple trades at prices ranging from $40.00 to $40.79; weighted-average price $40.32. (Footnote: reporting person can provide per-trade price breakdown on request.)
• Total value: $17,175,244.
• Shares owned after transaction: not specified in the excerpt of the filing provided.
• Plan/authority: Sales were made pursuant to a Rule 10b5‑1 trading plan adopted November 21, 2025 (pre-arranged plan).
• Ownership structure/disclaimer: Shares are directly held by Third Rock Ventures V, L.P.; related general partner entities disclaim beneficial ownership except to the extent of pecuniary interest. Related Third Rock entities and GP entities also disclaim being part of a Section 13(d) group.
• Filing timeliness: The Form 4 was filed April 21, 2026 for the April 17 transaction. Form 4s are generally required within two business days of the transaction, so this filing appears to have been submitted after that typical window.

Context

• This transaction was an institutional sale by a 10% owner and was executed under a Rule 10b5‑1 plan (a pre-scheduled trading arrangement). Such sales are commonly scheduled for liquidity and do not, by themselves, indicate the insider’s current view of company prospects.