ORBIMED ADVISORS LLC 4

4 · Sionna Therapeutics, Inc. · Filed Jul 2, 2026

AI-generated summary of this filing

Updated Jul 2, 2026

Sionna (SION) Director OrbiMed Advisors Sells 115,844 Shares

What Happened

OrbiMed Advisors LLC, listed as a director-level reporting person for Sionna Therapeutics (SION), sold 115,844 shares of Sionna common stock in an open‑market/private sale on June 30, 2026. The shares were sold at $45.50 per share for total proceeds of approximately $5,270,902. The filing indicates the trades were made pursuant to a pre-established 10b5‑1 plan.

Key Details

Transaction date & price: 2026-06-30 — 115,844 shares sold at $45.50 each.
Proceeds: ~$5,270,902.
Filing date / report period: Form 4 filed July 2, 2026; Period of Report 2026-06-30. Filing appears timely (filed within the standard two-business-day window).
Shares owned after transaction: Not specified in the provided filing.
Notable footnotes:
- F1: Sale executed pursuant to a 10b5‑1 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 but disclaim beneficial ownership except for any pecuniary interest.
- F3: This Form 4 is jointly filed by OrbiMed Advisors and OrbiMed Capital GP VIII LLC; a representative (Peter A. Thompson) serves on Sionna’s board.
Reporting type: Institutional/investor entity (OrbiMed), not an individual executive; treated differently from insider executive buying/selling.

Context

Sales under 10b5‑1 plans are pre-arranged and often scheduled in advance, so they can be routine and do not necessarily signal a change in insider sentiment. Because this is an institutional holder/affiliate transaction (with record ownership through a fund entity), the filing’s disclaimers clarify the limited beneficial‑ownership assertion.

Form 4

Period: 2026-06-30

Director

Transactions

Sale
Common Stock
[F1][F2][F3]
2026-06-30$45.50/sh−115,844$5,270,902→ 2,555,877 total(indirect: See footnotes)

Footnotes (3)

[F1]These securities were sold pursuant to a 10b5-1 plan.
[F2]These securities are held of record by OrbiMed Private Investments VIII, LP ("OPI VIII"). OrbiMed Capital GP VIII LLC ("GP VIII") is the general partner of OPI VIII and OrbiMed Advisors LLC ("OrbiMed Advisors") is the managing member of GP VIII. By virtue of such relationships, GP VIII and OrbiMed Advisors may be deemed to have voting and investment power with respect to the shares held by OPI VIII and as a result may be deemed to have beneficial ownership of such shares. OrbiMed Advisors exercises investment and voting power through a management committee comprised of Carl L. Gordon, Sven H. Borho, and W. Carter Neild, each of whom disclaims beneficial ownership of the shares held by OPI VIII.
[F3]This report on Form 4 is jointly filed by OrbiMed Advisors and GP VIII. Each of the Reporting Persons disclaims beneficial ownership of the securities reported herein for purposes of Rule 16a-1(a) under the Securities Exchange Act of 1934, as amended (the "Exchange Act"), except to the extent of its pecuniary interest therein, if any. The Reporting Persons have designated a representative, Peter A. Thompson, a member of OrbiMed Advisors, to serve on the Issuer's board of directors. This report shall not be deemed an admission that any such entity or person is a beneficial owner of such securities for purposes of Section 16 of the Exchange Act, or for any other purpose.

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