Thompson Peter A. 4

4 · Sionna Therapeutics, Inc. · Filed Jul 9, 2026

AI-generated summary of this filing

Updated Jul 9, 2026

Sionna (SION) Director Peter A. Thompson Sells 85,918 Shares

What Happened

Peter A. Thompson, a director of Sionna Therapeutics, sold 85,918 shares on July 7, 2026. The shares were sold at $44.86 per share for total proceeds of $3,854,281. This was a sale (not a purchase or award).

Key Details

Transaction date and price: 2026-07-07 at $44.86 per share.
Total value: $3,854,281 (85,918 shares × $44.86).
Shares owned after transaction: Not specified in the Form 4. The reported shares were held of record by OrbiMed Private Investments VIII, LP; see footnotes.
Notable footnotes:
- F1: Sale executed pursuant to a prearranged 10b5-1 trading plan.
- F2/F3: Shares are held of record by OrbiMed Private Investments VIII, with OrbiMed entities and the reporting person linked by management relationships; the reporting parties disclaim beneficial ownership except to the extent of any pecuniary interest.
Filing timeliness: Form 4 was filed July 9, 2026 for a July 7 transaction, which appears to be timely (within the standard two business days required under Section 16).

Context

10b5-1 plan: The sale was made under a prearranged plan, which typically means the trade was scheduled in advance and not an ad hoc decision based on current company developments.
Institutional/manager role: The transaction involves securities held by an institutional vehicle (OrbiMed Private Investments VIII) and related managerial relationships; this may reflect an institutional disposition rather than a direct personal sale by an individual executive.

Form 4

Period: 2026-07-07

Director

Transactions

Sale
Common Stock
[F1][F2][F3]
2026-07-07$44.86/sh−85,918$3,854,281→ 2,469,959 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. The Reporting Person is a member of OrbiMed Advisors.
[F3]Each of the Reporting Person, OrbiMed Advisors, and GP VIII 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. 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.

Signature

/s/ Peter A. Thompson|2026-07-09

1 file