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Spero TherapeuticsSPRO +1.28%60 3-Year Share Buyback Ratio is -2.50 as of Mar. 2026. GuruFocus rates SPRO with a GF Score™ of 60/100 and a GF Value™ of $1.05 (Significantly Overvalued). The stock has 5 warning signs investors should review. Among 1,197 Biotechnology companies, Spero Therapeutics ranks better than 75.27% on this metric.
Shares Outstanding (EOP) are shares that have been authorized, issued, and purchased by investors and are held by them.
3-Year Share Buyback Ratio measures the average annual proportion of a company's outstanding shares repurchased over the past three years. It is calculated as the annualized percentage change in shares outstanding from three 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 3-Year Share Buyback Ratio was -2.50%.
The historical rank and industry rank for Spero Therapeutics's 3-Year Share Buyback Ratio or its related term are showing as below:
SPRO'
s 3-Year Share Buyback Ratio Range Over the Past 10 Years
Min: -39.8 Med: -20.45 Max: -2.5
Current: -2.5
During the past 11 years, Spero Therapeutics's highest 3-Year Share Buyback Ratio was -2.50%. The lowest was -39.80%. And the median was -20.45%.
SPRO's 3-Year Share Buyback Ratio is ranked better than 75.27% of 1197
companies
in the Biotechnology industry
Industry Median: -11.8
vs SPRO: -2.50
Spero Therapeutics (NAS:SPRO) 3-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 3-Year Share Buyback Ratio Related Terms
SPRO vs VXRT, ADCT, GNLX: 3-Year Share Buyback Ratio Comparison
For the Biotechnology subindustry, Spero Therapeutics's 3-Year Share Buyback Ratio, along with its competitors' market caps and 3-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 3-Year Share Buyback Ratio vs Biotechnology Industry
For the Biotechnology industry and Healthcare sector, Spero Therapeutics's 3-Year Share Buyback Ratio distribution charts can be found below:
* The bar in red indicates where Spero Therapeutics's 3-Year Share Buyback Ratio falls into.
Spero Therapeutics 3-Year Share Buyback Ratio Calculation
This is the annualized percentage change in shares outstanding from three years ago to the current year. The annualized percentage change is calculated with expontential compound based on the latest four 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 3-Year Share Buyback Ratio of -2.50 mean?
Spero Therapeutics (SPRO) has a 3-Year Share Buyback Ratio of -2.50 as of Mar. 2026. The 3-Year Share Buyback Ratio measures the average annual proportion of a company's outstanding shares repurchased over the past three years. It is calculated as the annualized percentage change in shares outstanding from three years ago to the current year. View historical data for Spero Therapeutics and its competitors. According to the industry distribution chart, Spero Therapeutics ranks #296 out of 1197 companies in the Biotechnology industry, placing it in the top 24.7%.
Is Spero Therapeutics' 3-Year Share Buyback Ratio too high?
Spero Therapeutics' current 3-Year Share Buyback Ratio is -2.50. Based on the distribution chart, Spero Therapeutics ranks #296 out of 1197 companies in the Biotechnology industry, which is in the top quartile — a strong position relative to peers. Overall, Spero Therapeutics has a GF Score™ of 60/100 and is considered Significantly Overvalued, reflecting its overall financial health beyond just this single metric.
How does Spero Therapeutics' 3-Year Share Buyback Ratio compare to VXRT and ADCT?
According to the Biotechnology industry distribution chart, Spero Therapeutics ranks #296 out of 1197 companies for 3-Year Share Buyback Ratio. This places Spero Therapeutics in the top 25% of its industry — outperforming the majority of peers. See the competitive comparison table and distribution chart on this page for a detailed peer-by-peer breakdown.
What is a good 3-Year Share Buyback Ratio for a Biotechnology company?
A good 3-Year Share Buyback Ratio depends on the Biotechnology industry context. However, 3-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 3-Year Share Buyback Ratio mean?
A high 3-Year Share Buyback Ratio can signal that a stock is expensive relative to its fundamentals. The 3-Year Share Buyback Ratio measures the average annual proportion of a company's outstanding shares repurchased over the past three years. It is calculated as the annualized percentage change in shares outstanding from three years ago to the current year. View historical data for Spero Therapeutics and its competitors. Spero Therapeutics's current 3-Year Share Buyback Ratio is -2.50. 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 Significantly Overvalued. The stock's GF Value™ is $1.05, compared to a current price of $1.58 — trading 50.5% above its estimated fair value. The current 3-Year Share Buyback Ratio is -2.50. Spero Therapeutics' overall GF Score™ is 60/100 with 5 warning signs to review. Investors should evaluate multiple metrics — including profitability, growth, and financial strength — before making a decision.
How is 3-Year Share Buyback Ratio calculated?
3-Year Share Buyback Ratio is calculated from a company's financial statements. For Spero Therapeutics (SPRO), the current 3-Year Share Buyback Ratio is -2.50 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 $1.58 is trading 50.5% above its estimated GF Value™ of $1.05.
GuruFocus considers Spero Therapeutics to be Significantly Overvalued.
Key valuation signals for SPRO:
3-Year Share Buyback Ratio: -2.50
GF Value™: $1.05 vs. price of $1.58 (50.5% 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.
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