Spero Therapeutics, Inc. (SPRO) - Dilution Analysis

Visualizing historical and potential share dilution over time

Dilution Analysis

Low Risk
Limited dilution potential
Last updated: May 13, 2026

Risk Assessment Details

Potential Dilution: 0.0% of current shares
Recent Dilution: 9.32% (2 years)
Historical Dilution Factor: minimal recent dilution
Outstanding Shares
57M
Potential Supply
0
Additional shares possible
Splits
None
Past 2 years

Summary

SPRO currently has 57.3M outstanding shares. with minimal authorized share overhang for future dilution. The company has minimally diluted shareholders by 9.32% over the past 2 years.

Share Structure Timeline

Outstanding Shares
Total Supply

Historical Data Points

Date Event Outstanding Supply
May 13, 2026

10-Q filing | 57.3M shares outstanding

57M 0
Mar 26, 2026

10-K filing | 59.0M shares outstanding

59M 0
Nov 13, 2025

10-Q filing | 56.3M shares outstanding

56M 0
Aug 12, 2025

10-Q filing | 56.0M shares outstanding

56M 0
May 13, 2025

10-Q filing | 55.4M shares outstanding

55M 0
Mar 27, 2025

10-K filing | 54.0M shares outstanding

54M 0
Nov 14, 2024

10-Q filing | 54.1M shares outstanding

54M 0
Aug 05, 2024

10-Q filing | 54.0M shares outstanding

54M 0
May 15, 2024

10-Q filing | 53.5M shares outstanding

54M 0
Mar 15, 2024

S-3 filing: Spero Therapeutics, Inc. intends to offer up to $300,000,000 of any combination of common stock, preferred stock, or debt securities.

53M 0
Mar 13, 2024

10-K filing | 53.0M shares outstanding

53M 0
Nov 13, 2023

10-Q filing | 52.7M shares outstanding

53M 0
Aug 10, 2023

10-Q filing | 52.6M shares outstanding

53M 0
May 11, 2023

10-Q filing | 52.5M shares outstanding

53M 0
Mar 30, 2023

10-K filing | 52.6M shares outstanding

53M 0
Nov 14, 2022

10-Q filing | 51.8M shares outstanding

52M 0
Aug 10, 2022

10-Q filing | 33.0M shares outstanding

33M 0
May 16, 2022

10-Q filing | 32.8M shares outstanding

33M 0
Mar 31, 2022

10-K filing | 32.8M shares outstanding

33M 0
Nov 10, 2021

10-Q filing | 32.3M shares outstanding

32M 0
Aug 05, 2021

10-Q filing | 32.1M shares outstanding

32M 0
May 06, 2021

10-Q filing | 29.7M shares outstanding

30M 0
Mar 11, 2021

10-K filing | 29.5M shares outstanding

30M 0
Mar 11, 2021

S-3 filing: Spero Therapeutics, Inc. is offering up to $300,000,000 of any combination of common stock, preferred stock, and debt securities from time to time at prices and on terms to be determined at or prior to the time of the offering.

29M 0
Nov 05, 2020

10-Q filing | 27.2M shares outstanding

27M 0
Aug 06, 2020

10-Q filing | 21.2M shares outstanding

21M 0
May 08, 2020

10-Q filing | 20.6M shares outstanding

21M 0
Mar 16, 2020

10-K filing | 20.3M shares outstanding

20M 0
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