Sionna Therapeutics

SION · NASDAQ

$4.15+$0.14 (+3.49%)TodayMarket closed · Oct 20, 7:30 PM ET

Prev close $4.01

Who owns SION

Largest institutional holders, from their latest 13F filings

The 10 largest institutions hold 74.5% of SION’s shares.

RA Capital Management, LP21.9%
TPG Capital, L.P.14.4%
Viking Global Investors LP7.1%
Atlas Venture6.6%
Next 6 largest institutions24.5%
All other shareholders25.5%

Top institutional holders of SION
Holder	Shares	% of shares	Change, last filing	Filed
RA Capital Management, LP	9.91M	21.94%	+0	Jun 30, 2026
TPG Capital, L.P.	6.49M	14.39%	+0	Jun 30, 2026
Viking Global Investors LP	3.20M	7.08%	+0	Jun 30, 2026
Atlas Venture	3.00M	6.63%	+0	Jun 30, 2026
Enavate Sciences GP, LLC	2.48M	5.49%	+0	Jun 30, 2026
OrbiMed Advisors, LLC	2.47M	5.47%	−85.92K	Jul 7, 2026
Qatar Investment Authority	2.02M	4.47%	−189.52K	Mar 31, 2026
Adage Capital Management, L.P.	1.60M	3.54%	+1.45M	Jun 30, 2026
BlackRock Institutional Trust Company, N.A.	1.32M	2.92%	+150.43K	Jun 30, 2026
Jennison Associates LLC	1.17M	2.60%	−279.09K	Jun 30, 2026

Largest mutual fund holders

Top mutual fund holders of SION
Holder	Shares	% of shares	Change, last filing	Filed
Vanguard Total Stock Market Index Fund	934.64K	2.07%	+0	Jul 31, 2026
State Street SPDR S&P Biotech ETF	683.48K	1.51%	+45.87K	Aug 31, 2026
Eventide Healthcare & Life Sciences Fund	644.52K	1.43%	+5.48K	Mar 31, 2026
PGIM Jennison Health Sciences Fund	489.54K	1.08%	−37.18K	Jul 31, 2026
iShares Russell 2000 ETF	481.85K	1.07%	−2.11K	Jul 31, 2026

Insider trades

Form 4 filings by officers, directors and large holders

Over the last 6 months, insiders sold $67.27M (15 trades) of SION on the open market, with no buys.

Latest SION insider transactions
Insider	Date	Type	Shares	Price	Value
Fitzpatrick Jennifer	Sep 17, 2026	Other	103.14K	—	—
Fitzpatrick Jennifer	Sep 17, 2026	Award	103.14K	—	—
Fitzpatrick Jennifer	Sep 17, 2026	Award	28.13K	—	—
Fitzpatrick Jennifer	Sep 17, 2026	Award	28.13K	—	—
McKee Charlotte	Sep 17, 2026	Other	155.70K	—	—
McKee Charlotte	Sep 17, 2026	Award	155.70K	—	—
McKee Charlotte	Sep 17, 2026	Award	50.00K	—	—
McKee Charlotte	Sep 17, 2026	Award	50.00K	—	—
Ridloff Elena	Sep 17, 2026	Other	165.44K	—	—
Ridloff Elena	Sep 17, 2026	Award	165.44K	—	—

Short interest

Settled Sep 30, 2026

Shares short: 3.80M
Days to cover: 2.30
% of shares outstanding: 8.41%
Average daily volume: 1.65M
Change since last report: −4.2%

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