Orbimed Advisors LLC and Orbimed Capital Gp VIII LLC Sells $22.9M of Sionna Therapeutics Inc (SION) — SEC Form 4, Apr 16, 2026

Open-Market Net Sale · SEC Form 4

−$22,945,044

10b5-1 Plan

Equity position changed by -14.5%

Reporting Owners

Orbimed Advisors LLC

Director

Orbimed Capital Gp VIII LLC

Director

TXN 2026-04-16 · FILED 2026-04-16

Equity Position 3.02M sh 3,530,702 → 3,020,119

Equity Change -14.5% shares held after vs before

Filing Lag 0 business days within 2-day SEC deadline

Form 4 · Statement of Changes in Beneficial Ownership

Sionna Therapeutics Inc

SION CIK 0002036042

Reporting Owners

Name	Relationship
Orbimed Advisors LLC CIK 0001055951	Director
Orbimed Capital Gp VIII LLC CIK 0001845804	Director

Orbimed Advisors LLC at Sionna Therapeutics Inc Full insider history

Bought (12 mo) —

Sold (12 mo) $55,674,637

More from this insider at Sionna Therapeutics Inc

Non-Derivative Securities Transactions

Title	Date	Type	Shares	Price	Net Total	Post-Txn	Ownership
Common StockF1 F2 F3	2026-04-14	S - Sale 10b5-1	47,814 D	$44.51	-$2,128,201	3,482,888	Indirect See footnotes
Common StockF1 F2 F3	2026-04-15	S - Sale 10b5-1	235,863 D	$44.64	-$10,528,924	3,247,025	Indirect See footnotes
Common StockF1 F2 F3	2026-04-16	S - Sale 10b5-1	226,906 D	$45.34	-$10,287,918	3,020,119	Indirect See footnotes

Footnotes (3)

F1: These securities were sold pursuant to a 10b5-1 plan. Show more
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. Show more
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. Show more

Institutional Holders

Largest by reported value

5%+ Holders · 13D/G 6 filers

Latest Schedule 13D/G per filer; stakes the filer reported closed are left out.

Other insiders at Sionna Therapeutics Inc

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