Spero Therapeutics Inc. Common Stock (SPRO)

FairStock Score: 71/100 — STEADY

Key Financials

AI Analysis

AI-generated, general educational analysis — not personal investment advice.

I am wary of biotech stories where the numbers look cheap but the business is not yet durable. Spero is a 25-employee clinical-stage antibiotic developer. Its candidate Tebipenem HBr has completed a second Phase 3, but approval and commercialization remain uncertain. Filed figures show wild swings: in FY2023 the company had revenue of $933,000, net income of $22.8M, and diluted EPS of $0.43; in FY2024 revenue was $371,000, net loss was $68.6M, and diluted EPS was -$1.27; in FY2025 revenue was $12.6M, net income was $8.6M, and diluted EPS was $0.15. More recently, in fiscal Q1 2026, the quarter ended 2026-03-31, it lost $7.2M, or $0.13 per share, and in fiscal Q2 2026, the quarter ended 2026-06-30, it lost $9.6M, or $0.16 per share. That tells me FY2025 profitability was not a stable earnings stream. Financial health is mixed. The D/E ratio of 0.05 is low, and trailing free cash flow is $19.6M, a 29.2% FCF yield, which is attractive if repeatable. But FairStock's Altman Z-Score of -7.20 and Piotroski F-Score of 2/9 warn of distress and weak fundamental momentum. At the 2026-10-13 close of $1.15, FairStock's calculations show P/B of 1.51, P/E of 8.21, EV/EBITDA of 1.29, and PEG of 0.17; the Graham Number is $1.55, implying a 25.81% margin of safety. Those multiples rely on lumpy results. The company has no real moat unless its antibiotic earns regulatory exclusivity and commercial partners. As a Graham-style investor, I see a speculative turnaround: some asset support and low debt, but binary clinical and cash-burn risks. Price is cheap only if the pipeline succeeds.

In plain English: Spero Therapeutics is a small drug company trying to develop an oral antibiotic for hard-to-treat bacterial infections. It has very little steady sales and has lost money in the most recent filed quarters, though it did report a full-year profit in fiscal 2025 and has low debt. At $1.15, the shares look inexpensive against some simple value measures, but the business is very risky and its future depends on drug development milestones.

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Data as of 2026-10-13 close · note generated 2026-10-15 · model deepseek-flash

Sources (SEC EDGAR): fiscal Q2 2026 10-Q (period ended 2026-06-30) · fiscal Q1 2026 10-Q (period ended 2026-03-31) · fiscal Q3 2025 10-Q (period ended 2025-09-30) · fiscal Q2 2025 10-Q (period ended 2025-06-30) · FY2025 10-K (period ended 2025-12-31) · FY2024 10-K (period ended 2024-12-31) · FY2023 10-K (period ended 2023-12-31)

Fundamentals from company filings and market-data providers; prices are end-of-day, not real-time. AI-generated analysis is general and educational — not personal investment advice. Scoring methodology · Score test · Disclaimer