ORBIMED ADVISORS LLC 4

What Happened OrbiMed Advisors LLC, reported as a director-related reporting person for Sionna Therapeutics (SION), sold 101 shares of Sionna common stock in an open-market disposition on May 27, 2026. The shares were sold at $44.49 per share for a total reported proceeds of $4,493. The filing indicates the sale was made pursuant to a 10b5-1 trading plan.

Key Details

• Transaction date: 2026-05-27 (reported on Form 4 filed 2026-05-29). Filing appears timely (filed within two business days).
• Transaction type/code: S = Sale (open market/private sale).
• Price and proceeds: 101 shares × $44.49 = $4,493.
• Shares owned after transaction: Not specified in the provided filing excerpt.
• Notable footnotes:
  • F1: Sale executed under a 10b5-1 plan (prearranged trading plan).
  • F2: Shares are held of record by OrbiMed Private Investments VIII, LP; OrbiMed Advisors and related entities may be deemed to have voting/investment power through their GP/management roles.
  • F3: Form 4 is jointly filed by OrbiMed Advisors and the GP; each disclaims beneficial ownership except to the extent of pecuniary interest. Peter A. Thompson is OrbiMed’s designated board representative.

Context This is an institutional/manager sale executed under a 10b5-1 plan, which typically indicates preplanned, routine dispositions rather than discretionary, real-time decisions by an insider. The small dollar amount ($4.5k) is not a material stake change and, standing alone, is not a strong signal about company prospects.