NasdaqHealth CarePharmaceutical PreparationsWALTHAM, MA

Sionna Therapeutics, Inc. SION

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Estimated market cap $150.63M45.24M shares, shares as of Oct 30, 2026CIK 2036042

Insider trades, 12 mo

0 buys · 82 sells

$151.09M sold, open market

Congress trades, 24 mo

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No disclosed trades

13F holders, Q3 2026

28.9% of shares · 34 added

13F holders

…

Lobbying, 12 mo

—

No lobbying filings

Federal contracts, 12 mo

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None matched

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Latest 10-Q

Q3 2026

What changed in Sionna Therapeutics, Inc.'s latest quarterly report, compared with the one before.

Filed Nov 10, 2026 · Quarter ended Sep 30, 2026

Compared with the 10-Q for the quarter ended Jun 30, 2026. Sections compared: management's discussion, risk factors, legal proceedings and controls and procedures.

Read the 10-Q on sec.gov ↗Filing index ↗

Latest 10-Q

What changed in Sionna Therapeutics, Inc.'s latest quarterly report, compared with the one before.

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Insider trades

82 in 12 mo

Open-market trades from Form 4. 10b5-1 marks a plan set in advance.

No open-market insider trades reported since Sep 17, 2026. Insiders have two business days to file.

Recent insider trades

Ra Capital Management, L.P. Director, 10% owner	Sep 17 Form 4 ↗	Sale	−$21.6M 3.42M sh @ $6.32	-52.5%
Ra Capital Management, L.P. Director, 10% owner	Sep 17 Form 4 ↗	Sale	−$252.1K 33,800 sh @ $7.46	-52.5%
Peter A. Thompson Director	Jul 7 Form 4 ↗	Sale 10b5-1 plan	−$3.9M 85,918 sh @ $44.86	-93.5%
OrbiMed Capital GP VIII LLC Director	Jul 7 Form 4 ↗	Sale 10b5-1 plan	−$3.9M 85,918 sh @ $44.86	-93.5%
Jennifer Fitzpatrick Chief Legal Officer	Jul 6 Form 4 ↗	Sale 10b5-1 plan	−$446.9K 10,250 sh @ $43.60	-92.7%

All SION insider trades →Planned sales (Form 144): see notices

Insider trades

Open-market trades from Form 4. 10b5-1 marks a plan set in advance.

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13F holders

13.08M shares

79 funds report SION. Values checked against market prices.

Funds report more than 100% of shares (Q2 2026)

147 funds hold the stock.

Q3 2026: 29% · 5,560 of ~8,900 funds reported so far

Q2 202598%
Q3 2025>100%
Q4 202598%
Q1 2026>100%
Q2 2026>100%
Q3 2026 (so far)29%

Q3 2026. 21 new, 34 added to, 15 trimmed, 89 exited since Q2 2026.

Top 13F holders
#
1	Atlas Venture Life Science Advisors, LLC 13F ↗	3.00M	$15.8M	unchanged
2	BlackRock, Inc. 13F ↗	2.68M	$14.1M	+81.4%
3	Aberdeen Group plc 13F ↗	1.34M	$7.1M	+372.7%
4	Vanguard Capital Management LLC 13F ↗	1.19M	$6.3M	+5.1%
5	Acadian Asset Management LLC 13F ↗	553,956	$2.9M	New
6	Geode Capital Management, LLC 13F ↗	539,509	$2.8M	+18.0%
7	Walleye Capital LLC 13F ↗	453,319	$2.4M	+365.7%
8	Marshall Wace, LLP 13F ↗	444,016	$2.3M	+3424.2%
9	State Street Corp 13F ↗	377,179	$2.0M	-63.1%
10	Morgan Stanley 13F ↗	303,883	$1.6M	+101.2%

One of these funds reports its values in thousands of dollars; its figures are shown in dollars.

Download CSV Every fund that holds SION, not only these ten. A download holds at most 10,000 rows; narrow the filters to get a smaller slice.

13F holders

Funds that report this stock, checked against market prices.

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Trades by members of Congress

Disclosed in dollar ranges, up to 45 days after the trade.

No recent congressional trades for this company.

Trades by members of Congress

Disclosed in dollar ranges, up to 45 days after the trade.

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Lobbying

What Sionna Therapeutics, Inc. and its lobbying firms report each quarter.

No recent lobbying filings for this company.

Lobbying

What Sionna Therapeutics, Inc. and its lobbying firms report each quarter.

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Institutional ownership over time

How many funds reported holding the stock at the end of each quarter, and how many shares they held between them.

Funds holding the stock

Shares they report

Funds holding the stock by quarter

Q1 2025	47	—	41.49M	$434.1M
Q2 2025	65	+18	43.45M	$753.8M
Q3 2025	78	+13	44.82M	$1.3B
Q4 2025	101	+23	43.95M	$1.8B
Q1 2026	122	+21	45.64M	$1.8B
Q2 2026	147	+25	48.28M	$2.1B
Q3 2026	79	-68	13.08M	$68.8M

Each point is a quarter-end, from Q1 2025 to Q3 2026. A fund's 13F lists its long positions in US-listed securities as of the last day of the quarter and arrives up to 45 days later, so each point shows holdings at quarter-end, not on the day they were reported.

Common shares only; options and bonds are left out. When a fund amends a report, the amended version is the one counted.

The history follows the company's current CUSIP number (829401108). If the company's shares were ever re-issued under a different CUSIP, the quarters before the change are not part of this series, so the first point (Q1 2025) can be later than the stock's first appearance in 13F reports.

Share counts are adjusted for stock splits; none took place between these quarters. Values are in dollars as reported at the time and are not adjusted.

A quarter appears once our daily update has built its summary. If a summary cannot be built, older reports are kept and the chart shows the quarters it has until the next update repairs it.

Institutional ownership over time

How many funds reported holding the stock at the end of each quarter, and how many shares they held between them.

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More filings and data

Each opens the table.

Ownership stakes5 in 12 mo 8-K events2 in 90 days Patents2 patents granted Short interestFINRA · updated Oct 15 Planned insider salesForm 144 · 29 in 12 mo Executive payNone on record Wikipedia attentionNone on record SEC enforcementNone on record Clinical trials0 active IPO history1 registration Ownership stakes…8-K events…Patents…Short interest…Planned insider sales…Executive pay…Wikipedia attention…SEC enforcement…

About the company

The basics from the company’s SEC registration.

Legal name: Sionna Therapeutics, Inc.
Address: 21 HICKORY DRIVE, SUITE 500, WALTHAM, MA 02451
Phone: 617-819-2020
Fiscal year ends: Dec 31
Filer category: Non-accelerated filer, smaller reporting company, emerging growth company
Incorporated in: DE
Listed as: SION (Nasdaq)
SEC filings: All filings on SEC EDGAR ↗

About the company

The basics from the company’s SEC registration.

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$3.33−$0.10 (−2.92%) Nov 13 close

1M3M1Y

Oct 13, 2026Low $3.28 · High $4.38Nov 13, 2026

Aug 13, 2026Low $3.28 · High $8.26Nov 13, 2026

Nov 13, 2025Low $3.28 · High $51.04Nov 13, 2026

Congress purchase Congress sale Insider sale over $1M

Adjusted for stock splits; not for dividends. Where prices come from.

Live chart

Intraday and historical prices from TradingView. Quotes may be delayed.

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Information, not investment advice. Company matching is automatic; check the source before relying on one row.