Sionna Therapeutics (SION) stock

Cystic fibrosis medicines , market cap $148M

Medicines for cystic fibrosis

Worth $148M

$3.70

+3.64%

As of Tuesday's close · Live for Pro members at the open

Why is SION down?

Down 30% in 3 months, 31% under its 50-day average.

Down more than its industry: the 274 other stocks in it fell a median 13% over the same 3 months.

−2Long-term trend below a falling 200-day average, down over one year

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4 more things pulling SION's score down, for Pro members.

Quality Score

-3

Poor

In its industry

#187of 281

Biotech

Checks firing

4of 14

Trending down

From 52-week high

-93.3%

under its best in a year

SION's Quality Score rose 1 point on Tue, Nov 10, to -3. The Sep 17 sale of $21.6M by RA Capital Management, L.P. (10% owner) counts for less as it ages.

Follow SION's news. Pro members can get an alert when Sionna Therapeutics files news, and see its trials, share raises, and its CEO's filings.

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We do the work for you. Every stock is scored and ranked, every 15 seconds while the market is open. Here it's 15 minutes behind. Pro members see it live.

NextQ1 2027“…combination to AscenSION CF Phase 2 proof-of-concept trial, expected to initiate in the first quarter of 2027”Trial start · SEC filing · Nov 10

Cash$268M, about 14 quarters (3.5 years) at the last year's spendingOn Jun 30 · the company says “into the second half of 2029”

Key facts on SION

Key facts on SION
Holding it back	Moves 10.6% a day with no profit behind it
Latest filing	8-K, Nov 10 Reported its quarterly results

1 more reason behind SION's -3, free with an account →3 more reasons behind SION's -3, for Pro members.

SION in the news

ReportThis morning: a loss of $0.72 a share. Past reports ›

What's next

Tue Nov 10: Stifel Healthcare Conference 2026Investor conference · date confirmed.

Expected to report Mon Mar 1, before the open

After its last 4 reports it closed -2.4% on average, higher 2 of 4 times.

Tested. Our top-scored stocks returned 2.2x the average stock over the next month. Reconstructed after the fact; recorded live since Sep 9, 2026. How we tested it

Cash$268M, about 14 quarters (3.5 years) at the last year's spendingOn Jun 30 · the company says “into the second half of 2029”

SION catalysts

Coming up

What's next for SION, and how long its cash lasts

Next step the company has named

Q1 2027“Advancing SION-451 + SION-2222 dual combination to AscenSION CF Phase 2 proof-of-concept trial, expected to initiate in the first quarter of 2027”Trial start · SEC filing · Nov 10

What it means: when a trial begins, or reaches the stage the company named.

Lead program: SION-451

For Pro members: 14 filings.

Cash runway Jun 30 balance sheet

About 14 quarters

$268M in cash and investments (as the company counts them), at its spending over the last year

What it means: how long the cash would last at the same pace, before any new money. The company's estimate is “into the second half of 2029” (8-K, Nov 10).

For Pro members: the cash used each quarter, and the math.

Dilution on the horizon

Shelf registration (S-3ASR, filed Mar 2, 2026)
At-the-market share sales program (S-3ASR, filed Mar 2, 2026)

For Pro members: 1 raise and its amount, and the share count against a year ago.

Insiders

Director RA CAPITAL MANAGEMENT, L.P. sold 3,448,811 shares on Sep 17. 16 more insider trades this year.

From Form 4: open-market buys and sales only.

Get an alert when Michael Cloonan buys or sells

For Pro members: every trade, and Michael Cloonan’s 16 filings and quotes.

Get an alert when SION files newsA free account. No card.

See every upcoming FDA date →

FDA dates in the next 60 days

Decision dates and advisory committee meetings the companies have announced in their filings, soonest first and small companies first.

DateStockDrug

In 12 daysFDA decisionIn 12 days · FDA decisionCAPRCapricor TherapeuticsDeramiocelCAPRCapricor Therapeutics · $500MDeramiocelFDA decision due (PDUFA)
In 12 daysFDA decisionIn 12 days · FDA decisionSVRASavaraMolgramostimSVRASavara · $900MMolgramostimFDA decision due (PDUFA)
In 42 daysFDA decisionIn 42 days · FDA decisionMLYSMineralys TherapeuticsLorundrostatMLYSMineralys Therapeutics · $1.3BLorundrostatFDA decision due (PDUFA)

14 more FDA dates and 103 trial data dates in the next 60 days, each on the FDA calendar. Pro members see whether each company's cash lasts past its date, with an optional alert before it. See all 151 dates, ranked →

How SION ranks in Biotech

SION is #187 of 281 by Quality Score.

How SION ranks in Biotech
Rank	Stock	Checks	Quality Score
1	ONCBeOne Medicines	8/14	24
2	VCELVericel	8/14	22
3	ETONEton Pharmaceutcials	9/14	20
	SEPNSepterna		Open for its score
	SGMTSagimet Biosciences		Open for its score
	SLDBSolid Biosciences		Open for its score
	SLNSilence Therapeutics		Open for its score
187	SIONSionna Therapeutics	4/14	-3

When does SION report earnings, and what happens after?

Expected to report Mon Mar 1, before the open (in 111 days).

What an earnings report is: every 3 months, a company tells everyone how much it sold and earned. We read the figures, the outlook, and how the stock moved after.

What SION reported on Nov 10, 2026

The quarter

A loss of $0.72 a share, from $0.46.

“This increase was primarily driven by development expenses incurred during the period, personnel-related costs, including stock-based compensation expenses, and restructuring related costs associated with the workforce reduction.”

The quarter that ended Sep 30, from the company's press release

The press release The filing on EDGAR

Where the sales came from

SION's results filing gives no sales by line in a table we read.

The outlook

No outlook figures read from this release.

In the company's words

“This increase was primarily due to personnel-related costs, including stock-based compensation expenses, and restructuring related costs associated with the workforce reduction.”

From its results filing (SEC filing · Nov 10)

The numbers

Market value: $148M; today
Free cash flow: -$76.2M; last 12 months

No analyst estimates on Breakaway: every figure here is filed.

The whole report on SION: every line of its sales, every outlook beside the one it replaced, and the company's words, for Pro members.

Close after the report, last 3

-10.9%+4.8%+3.6%

May 12Aug 6Nov 10

Reported	When	Gap	Reaction	5 days
Nov 10, 2026Before open	Before open	-2.2%	+3.6%	not yet
Aug 6, 2026Before open	Before open	-0.5%	+4.8%	-86.8%
May 12, 2026Before open	Before open	-1.9%	-10.9%	-14.6%

SION closed higher after 2 of its last 4 reports.

All 4 reports, and SION's Quality Score going into each

SION has 4 of 14 chart checks firing

Trend1 of 5 shown

MA FAN 21 EMA W.EMA HH/HL 52W HI

Volume1 of 3 shown

VOL VDU U/D VOL

Tight range1 of 3 shown

ATR SQZ SQUEEZE NR7

Buying1 of 3 shown

OBV+CLOSE HI SPRING

The other 10 checks on SION, and all 14 on every stock.Get in free →

SION RSI today: 36.7, below its 50-day and 200-day averages

Not scored

RSI 36.7, MACD above signal, below both averages. Not scored.13 readings

The deep dive on SION

What it does and how it makes money2 findingsFor Pro members2 findings on what SION does and how it makes money, for Pro members
Where it stands3 findings1 offering of shares or notes since Feb 2025, $191M in all.SEC filing · Feb 7, 2025
Who holds and trades it2 findingsFor Pro members2 findings on who holds and trades SION, for Pro members

6 more findings on SION, each with its source, for Pro members.

SION share count over time

2% more shares than a year earlier.

Weighted shares, quarter to Jun 30, 2026, both from one filing

Shares of SION outstanding, as filed
Shares outstanding	As of
45.2M	Jul 31, 2026
45.2M	Apr 30, 2026
45M	Feb 20, 2026
44.6M	Oct 31, 2025

Offerings, shelves, and splits of SION, from its filings
From its filings	Filed
Registered shares for a later sale (S-3ASR)	Mar 2, 2026
Raised $190.6M in a sale of shares, about 129% of its market value	Feb 7, 2025
Registered shares for sale (S-1)	Jan 17, 2025

SION insider trades

One insider sold $21.8M across 2 filings in the last 6 months. No open-⁠market buys on record. The newest:

SellRA Capital Management, L.P.$21.6M10% ownerat $6.32 on Sep 17, filed Sep 21

SellRA Capital Management, L.P.10% owner$21.6Mat $6.32 on Sep 17, filed Sep 21

SION's officers and directors

Officers and directors with a Form 4 in the last 12 months.

Michael CloonanPresident & CEO · no trades on file
Elena RidloffCFO and CBO · no trades on file
Jennifer FitzpatrickCLO and Head of Program Mgmt. · 3 trades
Charlotte McKeeCMO and Head of R&D · no trades on file
Peter A. ThompsonDirector · 20 trades

See insider trades by person

Which ETFs hold SION?

In ETFs: SION is under 0.1% of VTI, the most of the 24 funds Breakaway covers, by their holdings as filed for Jun 30, 2026.

About Sionna Therapeutics

Sionna Therapeutics Inc is a clinical-stage biopharmaceutical company on a mission to revolutionize the current treatment paradigm for cystic fibrosis (CF) patients by developing novel medicines that normalize the function of the cystic fibrosis transmembrane conductance regulator (CFTR) protein to deliver clinically meaningful benefits to CF patients. CF is a progressive and life-threatening genetic disease caused by inherited mutations in the CFTR gene, which heads to insufficient CFTR function. The Company is managed as one operating segment focused on the research and development of cystic fibrosis therapies.

59 employeesWaltham, MAsionnatx.com

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Every line of the score
Price action, the company, and signals, each with its points, on SION and every other stock.
FDA dates, counted down
Each date in the company's words, its cash against the date, and an optional alert before it.
CEOs buying their own stock
Every CEO buy, biggest names first. Sort, filter, save the list, and set optional alerts.
Congress trades
A member's trades, newest first, each with its amount. Sort and filter the whole list.
14 chart checks, read for you
The ones firing on the stock, each in plain words, its rule a tap away.
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Who reports each day, and how each stock took its last four reports.
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What would turn SION's score around: 7 things
4 more filings explained, a plain line each
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BreakawaySep 21RA Capital Management, L.P. sold SION$21.6M at $6.32, filed Sep 21

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See SION's 14 chart checks

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Straight AnswersStraight Answers

As of Nov 10, 2026: SION's Quality Score is -3 (Poor), #187 of 281 in Biotech. Insiders sold $21.8M in the last 6 months (Form 4).

What does SION's Quality Score say?

SION scores -3 today, which Breakaway calls Poor. It is #187 of 281 in Biotech by Quality Score, with 4 of 14 chart checks firing. Down 30% in 3 months, 31% under its 50-⁠day average. Cash lasts about 14 quarters at its spending (to Jun 30). Breakaway does not say whether to buy any stock: the score does not know your situation, and it is not a recommendation to buy or sell anything. Please do your own research.

What is SION's Quality Score?

SION scores -3 today, which Breakaway calls Poor (below zero). That is #187 of 281 in Biotech by Quality Score. The score adds up the chart checks, the trend, the company's filed sales, its profits, the news, insider trades, and Congress trades. The section above lists the lines behind SION's -3.

Are insiders buying SION?

One insider sold $21.8M across 2 filings in the last 6 months. No open-⁠market buys on record. The newest is RA Capital Management, L.P., 10% owner, who sold $21.6M on Sep 17. Every filing, with the scored weight, for Pro members.

Are the prices delayed?

Only on the public pages, which run at least 15 minutes behind. Pro members, and anyone on a guest pass, see real-time prices: the scanner refreshes every 15 seconds, and your watchlist every few seconds, pre-market and after hours included.