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Shares Outstanding (EOP) are shares that have been authorized, issued, and purchased by investors and are held by them.
10-Year Share Buyback Ratio measures the average annual proportion of a company's outstanding shares repurchased over the past ten years. It is calculated as the annualized percentage change in shares outstanding from ten years ago to the current year. A positive ratio may indicate share buybacks over the period, while a zero or negative ratio may reflect no repurchases or potential share issuance. Spero Therapeutics's current 10-Year Share Buyback Ratio was -19.40%.
SPRO's 10-Year Share Buyback Ratio is ranked worse than 65.82% of 667
companies
in the Biotechnology industry
Industry Median: -11.7
vs SPRO: -19.40
Spero Therapeutics (NAS:SPRO) 10-Year Share Buyback Ratio Explanation
A negative number means the company might be issuing new shares. A positive number indicates that the company is buying back shares.
Be Aware
Investors usually like share buybacks. But as pointed by Warren Buffett, only if a company buys back shares at the prices below the stock's intrinsic value, it rewards remaining shareholders. If a company buys its overvalued stocks back, it destroys shareholder value.
Spero Therapeutics 10-Year Share Buyback Ratio Related Terms
SPRO vs ACRV, BSEM, RNTX: 10-Year Share Buyback Ratio Comparison
For the Biotechnology subindustry, Spero Therapeutics's 10-Year Share Buyback Ratio, along with its competitors' market caps and 10-Year Share Buyback Ratio data, can be viewed below:
* Competitive companies are chosen from companies within the same industry, with headquarter located in same country, with closest market capitalization; x-axis shows the market cap, and y-axis shows the term value; the bigger the dot, the larger the market cap. Note that "N/A" values will not show up in the chart.
Spero Therapeutics 10-Year Share Buyback Ratio vs Biotechnology Industry
For the Biotechnology industry and Healthcare sector, Spero Therapeutics's 10-Year Share Buyback Ratio distribution charts can be found below:
* The bar in red indicates where Spero Therapeutics's 10-Year Share Buyback Ratio falls into.
Spero Therapeutics 10-Year Share Buyback Ratio Calculation
This is the annualized percentage change in shares outstanding from ten years ago to the current year. The annualized percentage change is calculated with least-square regression based on the eleven years of annual data on Shares Outstanding (EOP).
Please click Growth Rate Calculation Example (GuruFocus) to see how GuruFocus calculates Wal-Mart Stores Inc (WMT)'s revenue growth rate. You can apply the same method to get the average dividends per share growth rate.
What does a 10-Year Share Buyback Ratio of -19.40 mean?
Spero Therapeutics (SPRO) has a 10-Year Share Buyback Ratio of -19.40 as of Mar. 2026. The 10-Year Share Buyback Ratio measures the average annual proportion of a company's outstanding shares repurchased over the past ten years. It is calculated as the annualized percentage change in shares outstanding from ten years ago to the current year. View historical data for Spero Therapeutics and its competitors. According to the industry distribution chart, Spero Therapeutics ranks #439 out of 667 companies in the Biotechnology industry, placing it in the top 65.8%.
Is Spero Therapeutics' 10-Year Share Buyback Ratio too high?
Spero Therapeutics' current 10-Year Share Buyback Ratio is -19.40. Based on the distribution chart, Spero Therapeutics ranks #439 out of 667 companies in the Biotechnology industry, which is below the industry midpoint. Overall, Spero Therapeutics has a GF Score™ of 66/100 and is considered Modestly Overvalued, reflecting its overall financial health beyond just this single metric.
How does Spero Therapeutics' 10-Year Share Buyback Ratio compare to ACRV and BSEM?
According to the Biotechnology industry distribution chart, Spero Therapeutics ranks #439 out of 667 companies for 10-Year Share Buyback Ratio. This places Spero Therapeutics in the lower half of its industry. See the competitive comparison table and distribution chart on this page for a detailed peer-by-peer breakdown.
What is a good 10-Year Share Buyback Ratio for a Biotechnology company?
A good 10-Year Share Buyback Ratio depends on the Biotechnology industry context. However, 10-Year Share Buyback Ratio should not be evaluated in isolation — investors should consider it alongside profitability, growth, and financial strength metrics. Use the industry distribution chart on this page to see where any company falls relative to its peers.
What does a high 10-Year Share Buyback Ratio mean?
A high 10-Year Share Buyback Ratio can signal that a stock is expensive relative to its fundamentals. The 10-Year Share Buyback Ratio measures the average annual proportion of a company's outstanding shares repurchased over the past ten years. It is calculated as the annualized percentage change in shares outstanding from ten years ago to the current year. View historical data for Spero Therapeutics and its competitors. Spero Therapeutics's current 10-Year Share Buyback Ratio is -19.40. However, context matters — high-growth companies often justify higher valuations. Always evaluate alongside other metrics like GF Score™ and GF Value™.
Is Spero Therapeutics stock overvalued right now?
Based on GuruFocus' analysis, Spero Therapeutics (SPRO) is currently considered Modestly Overvalued. The stock's GF Value™ is $1.05, compared to a current price of $1.21 — trading 14.8% above its estimated fair value. The current 10-Year Share Buyback Ratio is -19.40. Spero Therapeutics' overall GF Score™ is 66/100 with 5 warning signs to review. Investors should evaluate multiple metrics — including profitability, growth, and financial strength — before making a decision.
How is 10-Year Share Buyback Ratio calculated?
10-Year Share Buyback Ratio is calculated from a company's financial statements. For Spero Therapeutics (SPRO), the current 10-Year Share Buyback Ratio is -19.40 as of Mar. 2026. GuruFocus calculates this using data sourced from SEC filings and annual reports. See the calculation section and 30-year financial data on this page for the full breakdown.
Is Spero Therapeutics (SPRO) Overvalued in 2026?
Based on GuruFocus' analysis, Spero Therapeutics stock appears to be overvalued.
The current stock price of $1.21 is trading 14.8% above its estimated GF Value™ of $1.05.
GuruFocus considers Spero Therapeutics to be Modestly Overvalued.
Key valuation signals for SPRO:
10-Year Share Buyback Ratio: -19.40
GF Value™: $1.05 vs. price of $1.21 (14.8% above fair value)
No single metric tells the full story. See the SPRO stock analysis page for a complete view including 30-year financials, guru trades, and insider activity.
Spero Therapeutics Inc is a clinical-stage biopharmaceutical firm. It focuses on identifying, developing, and commercializing novel treatments for MDR (Multi-drug-resistant) bacterial infections and rare diseases. The company's product candidate, tebipenem pivoxil hydrobromide or tebipenem HBr, is designed to be an oral carbapenem-class antibiotic for use in adults to treat MDR Gram-negative infections. It is also developing SPR720, a novel oral antibiotic designed for the treatment of a rare, orphan disease caused by pulmonary non-tuberculous mycobacterial infections, or NTM disease. It is also focused on SPR206, a next-generation polymyxin investigational product candidate being developed as an IV-administered medicine to treat MDR Gram-negative infections in the hospital.
66GF Score
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10-Year Share Buyback Ratio is just one metric. See GF Value™, 30-year financials, guru trades, warning signs, and more.
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