Quick Answer
Spero Therapeutics, Inc. reported Shares Outstanding of 56.41 million shares for fiscal year 2025.
Spero Therapeutics, Inc. Shares Outstanding — Annual History
| Fiscal Year | Shares Outstanding | YoY Change |
|---|---|---|
| 2025 | 56.41M | +3.3% |
| 2024 | 54.59M | +3.0% |
| 2023 | 53.00M | +1.0% |
| 2022 | 52.46M | +61.9% |
| 2021 | 32.39M | +10.7% |
| 2020 | 29.26M | +52.5% |
| 2019 | 19.19M | +11.5% |
| 2018 | 17.21M | +19.7% |
| 2017 | 14.37M | — |
| 2016 | 0 | — |
Quarterly Shares Outstanding
| Quarter Ending | Shares Outstanding | YoY | QoQ |
|---|---|---|---|
| September 30, 2025 | 56.31M | +3.7% | +0.2% |
| June 30, 2025 | 56.19M | +4.0% | +0.5% |
| March 31, 2025 | 55.90M | +3.8% | +2.4% |
| December 31, 2024 | 54.59M | +3.0% | +0.5% |
| September 30, 2024 | 54.31M | +2.5% | +0.6% |
| June 30, 2024 | 54.01M | +2.7% | +0.3% |
| March 31, 2024 | 53.87M | +2.5% | +1.6% |
| December 31, 2023 | 53.00M | +1.0% | +0.0% |
- Spero Therapeutics, Inc. showed an increase of +3.3% in Shares Outstanding compared to the prior fiscal year.
- The most recent figure is from Spero Therapeutics, Inc.’s fiscal year 2025 report (Form 10-K), filed with the SEC on March 26, 2026.
- All figures are sourced from SEC EDGAR XBRL filings, last verified June 17, 2026.
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