Stock fact sheet · data as of
Spero Therapeutics, Inc. (SPRO): fair value, margin of safety and Wheel Score
Healthcare · Biotechnology · United States · Value
Is SPRO undervalued?
SPRO has a margin of safety of 71%: the stock closed at 1.12 on 16 Oct 2026 against a GLS average fair value of 3.81. 6 of the 7 valuation models that produced a number sit above the price. Our screens treat a discount this large as a strong starting point for a cash-secured put, not as a verdict - the fair value is a model output, and a wide gap can mean the models are missing something the market knows.
The 7 models disagree widely: GLS Growth gives 0.3728 while Graham Growth gives 7.29. A spread that wide means the average is sensitive to which methods you trust; the model table below shows where each one lands, and the Quote page lets you switch any of them off.
The nightly engine files SPRO under Value: positive earnings at a P/E of 18 or less.
Nine valuation models for SPRO
Each model turns the latest filed numbers into a value per share; the GLS fair value is the simple average of the ones that produce a positive number. The last two rows are shown for reference and never enter the average. The Quote page lets you switch any model off and add your own margin of safety.
| Model | Value | vs price | What it measures |
|---|---|---|---|
| DCF | - | - | Present value of the projected free cash flows, discounted at the cost of capital; no value tonight |
| Graham Number | 1.48 | +32% | The most a defensive investor pays for the earnings and book value per share |
| Graham Growth | 7.29 | +550% | Graham's growth formula: EPS × (8.5 + 2 × growth), adjusted for bond yields |
| Lynch | 3.18 | +184% | EPS × the earnings growth rate (PEG of 1), growth capped at 25% |
| GLS Growth | 0.3728 | -67% | EPS compounded ten years at the blended growth rate, discounted back at 15% a year |
| 10 Cap | 6.85 | +511% | Owner's earnings (operating cash flow less maintenance capex) capitalised at 10% |
| Payback Time | 6.10 | +445% | Eight years of compounded free cash flow: the price at which the business pays for itself |
| DDM | - | - | Dividend discount model: next year's dividend ÷ (10% − 3% growth); needs a dividend; no value tonight |
| EPV | 1.42 | +26% | Earnings power value: current EPS capitalised at 9% with no growth |
| Zombie (liquidation) | 0.9855 | -12% | Current assets less all liabilities, per share: the balance-sheet floor. Not in the average |
| Wall St target | 0.0000 | -100% | Analysts' average 12-month price target. Not in the average |
Quality and financial health
Financial health is average - SPRO passes 6 of the nine Piotroski tests, which passes the Sunday Scan's "6 or more" rule. The Financials tab on the Quote page shows which tests fail. The GLS Moat score is low at 1.8 out of 10, which says the ten-year record of revenue, earnings, margins and returns on capital has been inconsistent - growth and shocks rather than steady compounding.
Returns on capital are high - ROIC 13.8%, ROE 14.5%, ROA 12.4% - with debt at 0.05 times equity and a free-cash-flow yield of 30.0%.
Spero Therapeutics, Inc. pays no dividend, so the DDM model does not apply and a covered-call holder earns only the premium and any price gain. Revenue comes mainly from Collaboration Revenue Related Party 100% (quarter Q1 FY2026).
Institutional ownership scores 5/10, insider activity 1/10 and Congressional trading 5/10 on the GLS smart-money scales.
| Piotroski F-score | 6 / 9 | ROIC | 13.8% |
|---|---|---|---|
| GLS Moat | 1.8 / 10 | ROE | 14.5% |
| Debt / equity | 0.05 | ROA | 12.4% |
| Free-cash-flow yield | 30.0% | Payout ratio | 0% |
| Institutions | 5 / 10 | Insiders · Congress | 1 · 5 / 10 |
Wheel Score 56: Fair
SPRO scores 56 out of 100 on the Wheel Score (Fair band, 50-64): a usable but unremarkable fit for the wheel strategy. The parts: Value 25/25, Health 13/20, Moat 3/15, Premium 5/20, Stability 10/20. Moat (3/15) is where the points are missing.
Implied volatility is 205%, far above the range the wheel strategy is built for. The premium looks generous; the Wheel Score gives it only 5 of 20 Premium points because moves of that size can blow through any strike. Chain open interest is 8,670 contracts across all expiries - enough for the wheel at normal size.
Volume runs at 698k shares a day on a market cap of $65M, with a beta of 1.50 - a high beta, so the stock tends to move more than the market and a strike can be gapped through; the Stability part of the Wheel Score gives that 10 of 20.
| Part | Points | From | |
|---|---|---|---|
| Value | 25 / 25 | 71% margin of safety | |
| Health | 13 / 20 | Piotroski 6/9 | |
| Moat | 3 / 15 | moat 1.8/10 | |
| Premium | 5 / 20 | implied volatility 205% | |
| Stability | 10 / 20 | 698k shares/day, $65M cap, beta 1.50 |
The Wheel Score ranks ~7,400 US stocks for selling cash-secured puts and covered calls; it is updated nightly and is not a recommendation. The walkthrough lesson shows how the score fits into a trade, start to finish.
Upcoming events
The next earnings report is due on 12 Nov 2026 (after the close), 27 days away; a 30-45-day put sold today would expire after it, which is worth weighing against the premium.
Earnings, dividend, IPO, split and economic calendars for the whole market, filterable to your watchlists.
Similar stocks in Biotechnology
The 12 companies below are the closest to Spero Therapeutics, Inc. by market cap within the Biotechnology industry, each with its own fact sheet; the Compare page puts up to eight of them side by side.
| Stock | Close | Fair value | MoS | Wheel | Mkt cap |
|---|---|---|---|---|---|
| VRCA Verrica Pharmaceuticals Inc. | 3.83 | - | - | 40Weak | $66M |
| XBIT XBiotech Inc. | 2.16 | 4.08 | +47% | 36Weak | $66M |
| HYFT MindWalk Holdings Corp. | 1.40 | - | - | 34Weak | $66M |
| OSTX OS Therapies Incorporated | 1.41 | - | - | 26No options | $66M |
| PMVP PMV Pharmaceuticals, Inc. | 1.24 | 0.6530 | -90% | 18Weak | $66M |
| CING Cingulate Inc. | 4.39 | 0.0505 | -8592% | 24Weak | $64M |
| CSBR Champions Oncology, Inc. | 4.79 | 3.89 | -23% | 24Weak | $67M |
| FBIO Fortress Biotech, Inc. | 1.91 | 74.01 | +97% | 54Fair | $64M |
| TLSA Tiziana Life Sciences Ltd | 1.05 | 0.0186 | -5553% | 20Weak | $67M |
| AURX Nuo Therapeutics, Inc. | 1.28 | - | - | 25No options | $62M |
| MAIA MAIA Biotechnology, Inc. | 1.12 | 269.53 | +100% | 39No options | $69M |
| APLM Apollomics, Inc. | 21.00 | - | - | 28No options | $61M |
Screen the whole market the same way
A free GLS Equity account gets you nightly fair value and the Wheel Score on ~7,400 US stocks, a watchlist, the scanner preview and the Sunday Scan - the same eight-rule screen, emailed every week. Pro adds the full put and call scanners, unlimited watchlists with alerts and the trade journal.
Start free See the Sunday ScanQuestions about SPRO
Is SPRO undervalued right now?
By the GLS models, yes: at 1.12 the stock is 71% below the average fair value of 3.81 (data as of 16 Oct 2026). Whether the discount is deserved is the question to research next.
What is the Wheel Score of SPRO and what does it mean?
SPRO scores 56 out of 100 (Fair). The Wheel Score blends the margin of safety (25 points), Piotroski health (20), the GLS moat (15), the option premium on offer (20) and trading stability (20) into one number that ranks stocks for the wheel strategy - selling cash-secured puts, then covered calls if assigned. 80 and above is Prime, 65-79 Good, 50-64 Fair, under 50 Weak.
What is the GLS fair value for SPRO?
3.81 per share as of 16 Oct 2026 - the simple average of the 7 valuation models (out of nine: DCF, Graham Number, Graham Growth, Lynch, GLS Growth, 10 Cap, Payback Time, DDM and EPV) that produced a positive value. The models run every night on the latest filings; the Quote page lets you switch any of them off and add a margin of safety of your own.
When does Spero Therapeutics, Inc. report earnings next?
The next earnings report is due on 12 Nov 2026 (after the close), 27 days from the data date of 16 Oct 2026. The Calendars page lists every upcoming report with its time of day.
Does SPRO have listed options, and how liquid are they?
Yes. The nightly snapshot found 70 listed contracts with 8,670 open interest across all expiries and implied volatility of 205% on the near-the-money contracts. The Options scanner lists the cash-secured put and covered call set-ups with premium and annualised yield worked out.