$SION

$3.87 +$0.18 (4.88%) Close

$SION Overview Financial Statements SEC Filings Executives News Red Flags Capital Raising Ownership Insider Transactions Congressional Trades

Ownership

13F as of Q2 2026 · 45.2M shares outstanding

Who owns SION?

By type of holder

Institutions 100.0% Insiders 0.0% Everyone else 0.0%

Concentration Top 10 holders own 134.4%

Ra Capital Management, L.P. 21.9% · Thompson Peter A 19.6%

Institutional ownership

100.0%

0 pts vs last qtr

Institutional holders

145

+23 vs last qtr

Net shares bought

+2.7M

by institutions in Q2 2026

New / sold out

33 / 10

positions opened vs closed

How is ownership changing?

Institutions, last 8 quarters

Biggest buyers in Q2 2026

Adage Capital Partners GP, L.L.C. +1.5M
Casdin Capital, LLC NEW +400.0K

Biggest sellers in Q2 2026

Orbimed Advisors LLC −974.8K
Deerfield Management Company, L.P. −289.7K

Who is planning to sell?

Notices of proposed sale, last 12 months

$95.7M

28 notices from 10 people

Shares covered

5.2M

11.40% of the company

Arranged in advance

59%

of the value is under a 10b5-1 plan

Under a 10b5-1 plan No plan

Largest proposed sellers

OrbiMed Private Investments VIII, LP Shareholder 10b5-1 $55.5M
RA Capital Healthcare Fund, L.P. Director $21.8M

Every notice on Red Flags →

A Form 144 is notice of a planned sale, not the sale itself. What insiders actually sold is on Insider Transactions.

Is your stake being diluted?

Diluted share count, FY2024–FY2025

+935.6%

+935.60% a year

Each share's claim on the business

−90.3%

shrank without buying or selling a share

Spent on buybacks vs paid in stock

— vs $15.8M

over 2 fiscal years

Diluted shares, split-adjusted

Buybacks Stock-based comp

How patient are the owners?

Institutional shares by how long they've been held

5+ years0% 3–5 years0% 1–3 years88% Under 1 year12%

Quarterly turnover

9.6%

of institutional shares changed hands

Top 10 managers, median time held

1.3 years

Super Investors

Investment managers reporting SION on Form 13F

Holder	Shares	% of company	Change vs last qtr	Held since	% of their book
RC Ra Capital Management, L.P. 13D · 14.3%	9.9M	21.91%	Unchanged	2025	3.8%
Shares held by quarter Peak holding10.4M (Q1'25) Change over 8 quarters+9.9M Share of the company21.910% Disclosed stake13D · 14.3% Ra Capital Management, L.P.'s full portfolio →
TG TPG GP A, LLC 13D · 15.2%	6.5M	14.37%	Unchanged	2025	5.7%
Shares held by quarter Peak holding6.7M (Q2'25) Change over 8 quarters+6.5M Share of the company14.370% Disclosed stake13D · 15.2% TPG GP A, LLC's full portfolio →

Ra Capital Management, L.P.

13D · 14.3%

9.9M

% of company

21.91%

Change vs last qtr

Unchanged

Held since

2025

TPG GP A, LLC

13D · 15.2%

6.5M

% of company

14.37%

Change vs last qtr

Unchanged

Held since

2025

28 more super investors behind a free account

See every manager holding Sionna Therapeutics, Inc., how their position has changed, and how long they've held it.

Institutional Funds

Mutual funds and ETFs reporting SION on Form N-PORT; together they hold 15.0% of the company

Fund	Position value	Shares	% of company	% of the fund	As of
VT Vanguard Total Stock Market Index Fund Vanguard Index Funds	$41.1M	934.6K	2.07%	0.00%	June 30, 2026
SS State Street(R) SPDR(R) S&P(R) Biotech ETF SPDR Series Trust	$28.5M	647.7K	1.43%	0.27%	June 30, 2026

Vanguard Total Stock Market Index Fund

Vanguard Index Funds

Position value

$41.1M

% of company

2.07%

% of the fund

0.00%

As of

June 30, 2026

State Street(R) SPDR(R) S&P(R) Biotech ETF

SPDR Series Trust

Position value

$28.5M

% of company

1.43%

% of the fund

0.27%

As of

June 30, 2026

23 more funds behind a free account

See every fund holding Sionna Therapeutics, Inc. and how much of the fund the position is.

Insiders and 5%+ holders

From Forms 3/4/5 and Schedules 13D/G

Holder	Shares	% of company	Change vs last qtr	8 quarters	Held since	% of their book
TP Thompson Peter A Insider	8.8M	19.57%	—	—	—	—
Insider holdings come from Form 3/4/5 filings, which are not quarterly. Share of the company19.570% Thompson Peter A's insider activity →
JW Jon Winkelried 5%+ holder 13D · 15.2%	6.7M	14.79%	—	—	—	—
This holder reports through Schedule 13D/G, not a quarterly 13F. Share of the company14.790% Disclosed stake13D · 15.2% View the 13D/G filing →

Thompson Peter A

Insider

8.8M

% of company

19.57%

Change vs last qtr

—

Held since

—

Jon Winkelried

5%+ holder13D · 15.2%

6.7M

% of company

14.79%

Change vs last qtr

—

Held since

—

18 more holders behind a free account

See every insider and 5%+ holder of Sionna Therapeutics, Inc..

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