Thompson Peter A. 4

What Happened
Peter A. Thompson, a director of Sionna Therapeutics, sold a total of 55,345 shares in two transactions: 52,397 shares on 2026-04-17 at $44.68 each ($2,341,098) and 2,948 shares on 2026-04-18 at $44.52 each ($131,245), for combined proceeds of approximately $2,472,343. These were sales (not purchases) and were reported on a Form 4 filed 2026-04-21.

Key Details

• Transaction dates and prices:
  • 2026-04-17 — 52,397 shares sold at $44.68 ($2,341,098)
  • 2026-04-18 — 2,948 shares sold at $44.52 ($131,245)
• Total shares sold: 55,345; total proceeds: ~$2.47M.
• Shares owned after transaction: not specified in the provided filing.
• Notable footnotes:
  • F1: Sales were made pursuant to a 10b5‑1 trading plan.
  • F2–F3: The shares are held of record by OrbiMed Private Investments VIII, LP. OrbiMed Advisors and related entities are noted as having potential voting/investment power; the reporting person is a member of OrbiMed Advisors and the parties disclaim beneficial ownership except to the extent of any pecuniary interest.
• Timeliness: Form 4 was filed 2026-04-21 for trades dated 2026-04-17 and 2026-04-18; this filing appears to be within the standard SEC two-business-day reporting window.

Context: These are director sales under a pre-established 10b5‑1 plan, which are commonly used to execute routine dispositions and do not on their own indicate the director’s view of the company’s prospects. The filing involves institutional record ownership through OrbiMed entities with disclaimers about beneficial ownership.