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Sionna Therapeutics, Inc. (SION) fair value: what the stock is really worth

As of Oct 5, 2026: fair value of Sionna Therapeutics, Inc. $4.18, price $4.85, upside -13.8%, quality 39 out of 100. Calculated from audited financials with 26 valuation models and 37 quality factors, updated daily.

  1. Fair value above price? No
  2. Good quality? No
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Healthcare · US · ISIN US8294011080

ST Sionna Therapeutics, Inc. logo Thin data Sep 27, 2026

Sionna Therapeutics, Inc.

SION · US

Weak valuationQuality is weak on top of the rich price.

Mixed vs. peers (4/7)
Insider activity 44/100
Fair value $4.18 · Overvalued (−13.8%)
Quality 39/100
Negative free cash flow
Narrow moat 8/100
Thin data
⚠ Dilution
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What runs behind every stock

26 valuation models 8 families, DCF to NCAV 37 quality factors margins, balance sheet, cashflow, debt 6 AI factors moat, what no ratio measures 2,000+ data points verified, per stock, median

69 individual criteria per stock, every one traceable See the method →

Price vs Fair Value

$51.04 $4.50 Fair Value $4.18 Feb 2025 Oct 2026

White line = price, green steps = our fair value per fiscal year, dashed = 300-day average. As of Sep 27, 2026.

How to read this chart

20‑month range $4.50 – $51.04 · fair‑value band $2.76 – $5.23 · the $4.85 price screens above the $4.18 fair value. Dashed = 300-day average. As of Sep 27, 2026.

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Company profile

Sionna Therapeutics, Inc., a clinical-stage biopharmaceutical company, researches and develops medicines for the treatment of cystic fibrosis (CF).

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Sionna Therapeutics, Inc., a clinical-stage biopharmaceutical company, researches and develops medicines for the treatment of cystic fibrosis (CF). It develops galicaftor (SION-2222), a transmembrane domain 1 (TMD1)-directed cystic fibrosis transmembrane conductance regulator (CFTR) that has completed Phase 2 trial; navocaftor (SION-3067), a potentiator that has completed Phase 2 trial; SION-109, an intracellular loop 4 directed CFTR corrector that has completed Phase 1 trial; SION-2851, a TMD1-directed CFTR corrector that has completed Phase 1 trial; SION-451, which is nucleotide-binding domain 1 stabilizer in Phase 1 trial; and SION-719, which is nucleotide-binding domain 1 stabilizer in Phase 2a proof-of-concept trial. The company was formerly known as Sling Therapeutics, Inc. and changed its name to Sionna Therapeutics, Inc. in July 2021. Sionna Therapeutics, Inc. was incorporated in 2019 and is headquartered in Waltham, Massachusetts.

Stock analysis

Sionna Therapeutics, Inc. Common Stock (SION) currently trades at $4.85, while our model-based Fair Value estimate is $4.18, 13.8% below the price, so the stock looks overvalued today.

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Valuation

How firm this estimate is: it rests on 1 models at a data quality of 92/100, which puts the evidence level at low.

Scenario range: $2.76 (bear) to $5.23 (bull), the price of $4.85 sits inside it. Bear and bull are the same models on cautious and optimistic assumptions, a range, not a price target.

Quality & growth

The Quality Score stands at 39/100 (below-average quality), in the Healthcare sector.

Sionna Therapeutics, Inc. Common Stock reported revenue of $0 in FY2025 versus $0 in FY2022. Reported net income was −$75.3M in FY2025.

Key figures

Market cap $269M · EPS (TTM) $−2.15 · Return on equity −32.3% · Return on assets (EBIT) −52.4% · Free cash flow −$66.7M · Net cash $49.8M.

Competitive moat

Our AI-assisted moat analysis scores the competitive advantage at 32 out of 100 (low confidence).

What moves the price

The share trades about 90% below its 52-week high and 8% above its 52-week low.

For context, the median of 10 Healthcare peers we cover trades at 10% fair-value upside, at −14%, SION screens richer than that median.

Fair Value models

Bear $2.76 Fair Value $4.18 Bull $5.23
Price $4.85 · Upside -13.8%
Model ⓘEach model values the company its own way (discounted cash flow, earnings, assets, dividends). The fair value above is their evidence-weighted blend, not the output of a single model. Bear ⓘBear = the cautious scenario: the same model computed with conservative anchors (lower growth, margins and valuation multiples). Together with Bull it frames a plausible valuation range, not a price target.BaseBull ⓘBull = the optimistic scenario: the same model computed with favourable anchors (higher growth, margins and valuation multiples). Together with Bear it frames a plausible valuation range, not a price target. If a model's bull case is above four times its base value, the table shows that limit with a > sign (like the overall Bull above): beyond it no assumption holds. Evidence ⓘEvidence = how well-backed THIS model's estimate is for this stock (0–100): how complete and reliable its input data are, and how well the model fits the company. The final Fair Value is an evidence-weighted blend, so better-evidenced models count more. Green ≥70, amber 50–69, grey below 50.
Highest evidence
NCAV (Graham) $3.40 $4.55 $6.80 51
All 1 models by family
Asset-Based
NCAV (Graham) $3.40 $4.55 $6.80 51

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Quality Score breakdown

Overall quality 39/100

Of which business quality 39 · Market factors (momentum, volatility) 0

Profitability 0
Margins and returns on capital today
Quality Growth 75
Are margins and returns improving?
Cashflow 25
Earnings quality: real cash, not paper profit
Fin. Strength 90
Balance sheet, leverage, solvency risk
Investment 0
Disciplined investing over empire-building
Low Volatility 0
Calm price path (market factor)
Momentum 0
Price trend over the last 3–12 months (market factor)
52W Momentum 0
Distance to the 52-week high (market factor)
Net Issuance 38
Share count: buybacks or dilution?

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Revenue & earnings trend

What shareholders gained per year ⓘWe only publish this rate when it is defensible. Reason: fiscal 2025 is a loss year, no rate is defined from a loss
not computed

SION screens overvalued: fair value 14% below the price. Compare with Vertex Pharmaceuticals Incorporated →

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Peer GroupⓘHow this stock ranks against its industry: the green marker is this stock, the band is the typical 25–75% peer range, and the tick is the median.Biotechnology · 607 stocks

Beats the industry median on 4/6 measures
Overall it ranks above its industry peers.
Valuation
Quality Score 39 · Below median
Fair Value upside −13.8% · Above median
Profitability
Return on assets −21.5% · Below median
Operating margin (TTM) 0.0% · Above median
Growth and dividend
Revenue growth 0.0% · Above median

Valuation Multiplesvs Biotechnology median · lower = cheaper

P/B 0.88× · Cheaper than median

Strength profile in five axes (Snowflake)

VALUEFUTUREPASTHEALTHDIVIDEND
This stock
VALUEFUTUREPASTHEALTHDIVIDEND
Sector peers
VALUE (fair-value potential)15 · sector 0
FUTURE (revenue growth)0 · sector 0
PAST (return on equity)0 · sector 0
HEALTH (low debt)0 · sector 97
DIVIDEND (yield)0 · sector 22

Context: sector, industry, market

Values & ESG

Does this company touch areas you may want to avoid? The classification is inferred from sector and industry.

None of the checked exposures detected

Similar stocks

10 more Biotechnology stocks, each showing price versus our Fair Value estimate.

Stock Price Fair Value vs Fair Value
Vertex Pharmaceuticals Incorporated VRTX $504.73 $555.20 +10%
Regeneron Pharmaceuticals, Inc REGN $735.20 $1,275 +73%
argenx SE ARGX $959.49 $918.60 −4%
CSL Limited CSL A$175.35 A$192.89 +10%
Samsung Biologics Co 207940 1,354,000 KRW 1,489,400 KRW +10%
BeOne Medicines AG ONC $360.85 $280.94 −22%
Alnylam Pharmaceuticals, Inc ALNY $255.96 $217.88 −15%
Royalty Pharma plc RPRX $58.21 $19.01 −67%
Celltrion, Inc 068270 177,400 KRW 74,519 KRW −58%
WuXi Biologics (Cayman) Inc 2269 HK$53.00 HK$58.30 +10%

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Sionna Therapeutics, Inc. Common Stock · Fair Value
$4.18 −14%Fair Value
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Cite: Fair Value Calculator (2026). "Sionna Therapeutics, Inc. Common Stock Fair Value". https://www.fairvalue-calculator.com/stock/SION

Frequently asked questions

Is Sionna Therapeutics, Inc. (SION) overvalued or undervalued?
As of Sep 27, 2026, our model estimates a fair value of $4.18 versus a price of $4.85, about −14% upside (overvalued).
What is the fair value of SION?
Our model-based fair value for Sionna Therapeutics, Inc. Common Stock is $4.18 (as of Sep 27, 2026), built from audited fundamentals. The current price: $4.85.
What is the quality score of SION?
Sionna Therapeutics, Inc. Common Stock has a Quality Score of 39/100. It measures business quality (profitability, growth, cash flow, balance-sheet strength, investment discipline, share issuance). Market factors such as price momentum and volatility do not enter the number; they are shown separately in the detail view.
What is the price target for Sionna Therapeutics, Inc. (SION)?
Our model-based price target is the fair value of $4.18 (as of Sep 27, 2026) from 1 valuation models. Cautious scenario $2.76, optimistic scenario $5.23. It is a calculation from audited fundamentals, not an analyst target.
What is the Sionna Therapeutics, Inc. Common Stock stock forecast for 2026?
Our models put fair value at $4.18, about −14% upside versus a price of $4.85 (overvalued). Cautious scenario $2.76, optimistic scenario $5.23. The calculation is refreshed regularly with new filings.
What is the intrinsic value of Sionna Therapeutics, Inc. (SION)?
Intrinsic value and fair value mean the same thing: what the business is worth on its numbers, independent of the share price. For Sionna Therapeutics, Inc. Common Stock it is $4.18 per share (as of Sep 27, 2026), against a price of $4.85. It is the blended result of 1 valuation models (cash flow, earnings, asset, dividend).
Is Sionna Therapeutics, Inc. Common Stock stock overvalued or undervalued in 2026?
As of Sep 27, 2026, SION trades above its calculated fair value: price $4.85, fair value $4.18, a gap of about −14% (overvalued). The calculation is refreshed with each new quarterly report, so the verdict can change during the year.
Is fair value the same as the market price of SION?
No. The price is what the market pays today ($4.85); the fair value is what the company's own numbers justify ($4.18). For Sionna Therapeutics, Inc. Common Stock the two are $0.6680 per share apart. That gap is exactly why we show both numbers side by side.
How much is Sionna Therapeutics, Inc. Common Stock worth?
The market values Sionna Therapeutics, Inc. Common Stock at about $269M (market capitalisation, as of Sep 27, 2026). Per share that is $4.85; our models calculate a fair value of $4.18 per share.
What do the bullish and bearish scenarios say about SION?
Our models span a range for Sionna Therapeutics, Inc. Common Stock: cautious scenario $2.76, base $4.18, optimistic $5.23 per share (as of Sep 27, 2026, price $4.85). The range comes from different growth and margin assumptions, not from analyst opinions.
How solid is the balance sheet of Sionna Therapeutics, Inc. (SION)?
Balance-sheet figures for Sionna Therapeutics, Inc. Common Stock (as of Sep 27, 2026): return on equity −32.3%. They feed the Quality Score of 39/100, which measures business quality independently of the share price.
How far is SION from its 52-week high?
Sionna Therapeutics, Inc. Common Stock trades at $4.85, about 90% below its 52-week high of $51.04 and 8% above the low of $4.50 (as of Oct 5, 2026). Distance from the high says nothing about value: that is what the fair value of $4.18 is for.
Which stocks are comparable to Sionna Therapeutics, Inc. Common Stock?
From the same area (Healthcare) we also value Vertex Pharmaceuticals Incorporated, Regeneron Pharmaceuticals, Inc, argenx SE, CSL Limited, among others. Each of them has its own fair-value calculation on this site using the same models, so the comparison is like for like.
Is Sionna Therapeutics, Inc. Common Stock stock attractive at the current price?
The data as of Sep 27, 2026: price $4.85, calculated fair value $4.18 (−14%), Quality Score 39/100, from 1 models. Whether that fits your horizon and risk tolerance is your call. We provide the calculation, not investment advice.
How is the fair value of SION calculated?
We run Sionna Therapeutics, Inc. Common Stock through 1 models from four families: discounted cash flow, earnings models, asset and balance-sheet models, and dividend models. Every model gets the same audited fundamentals; the result is the weighted average of $4.18, with the spread shown as a cautious and an optimistic scenario.
Is it still worth investing in stocks now?
The global stock market currently sits 15.0 % above its aggregate fair value. Sionna Therapeutics, Inc. Common Stock itself currently trades above fair value. An expensive market is no reason to stay out and no reason to buy everything at once: keep a broad savings plan running, buy single stocks only with money you can do without, and hold part of your money liquid while the market is high. The full picture including sectors is on is it worth investing now.
What is the share price of Sionna Therapeutics, Inc. (SION)?
The closing price on Oct 5, 2026 was $4.85. Our model-based fair value is $4.18, about −14% upside (overvalued). We carry closing prices from our data provider, not a live tick.
What should I pay attention to with Sionna Therapeutics, Inc. Common Stock right now?
A fairly wide model range ($2.76 to $5.23) leaves room in how you read the outcome. Evidence is limited here (fewer models, shorter history), so the fair value is a rougher estimate than usual.

Key figures of Sionna Therapeutics, Inc. Common Stock

How large is the market capitalisation of Sionna Therapeutics, Inc. (SION)?
The market capitalisation of Sionna Therapeutics, Inc. Common Stock is $269M. The stock-market value of the whole company: share price times number of shares. It is what the market asks for the entire business today.
What are the earnings per share of Sionna Therapeutics, Inc. (SION)?
Earnings per share at Sionna Therapeutics, Inc. Common Stock are $−2.15. Earnings per share over the last twelve months: total profit spread across every single share.
What is the return on equity of Sionna Therapeutics, Inc. (SION)?
The return on equity (ROE) of Sionna Therapeutics, Inc. Common Stock is −32.3% (last twelve months). Profit relative to shareholders' equity, how efficiently the company works with its owners' money.
What is the EBIT return on assets of Sionna Therapeutics, Inc. (SION)?
On an EBIT basis the return on assets of Sionna Therapeutics, Inc. Common Stock is −52.4% (avg 4y). Operating profit (EBIT) relative to everything the company owns, as a multi-year average. It describes the business model rather than one good or bad year.
How much free cash flow does Sionna Therapeutics, Inc. (SION) generate?
The free cash flow of Sionna Therapeutics, Inc. Common Stock is −$66.7M (fiscal year 2025). The cash truly left after running and investing in the business, this is what pays dividends and buybacks.
How much net cash does Sionna Therapeutics, Inc. (SION) hold?
Sionna Therapeutics, Inc. Common Stock holds more cash than debt, $49.8M net (fiscal year 2025). The company holds more cash than debt, a safety cushion.
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