Spero Therapeutics, Inc. SEC filings SPRO
Spero Therapeutics, Inc. has 515 filings in SEC EDGAR's recent list, going back to Mar 21, 2017. Its latest annual report, Form ARS, was filed on Apr 27, 2026 for the period ended Dec 31, 2025. The latest quarterly report (Form 10-Q) was filed on Aug 12, 2026, covering the quarter ended Jun 30, 2026. The most recent current report (Form 8-K) was filed on Oct 27, 2026 (officer or director change). The company's fiscal year ends on December 31.
| Form | Description | Filed | Period |
|---|---|---|---|
| S-8 | Employee stock plan registration | Oct 28, 2026 | — |
| 8-K |
Current report
Officer or director change
|
Oct 27, 2026 | Oct 26, 2026 |
| EFFECT | Filing | Sep 10, 2026 | — |
| 8-K |
Current report
Material agreement, Other events
|
Aug 28, 2026 | Aug 28, 2026 |
| S-3 | Shelf registration | Aug 28, 2026 | — |
| 8-K |
Current report
Results of operations
|
Aug 12, 2026 | Aug 12, 2026 |
| 10-Q | Quarterly report | Aug 12, 2026 | Jun 30, 2026 |
| 4 | Insider transaction | Aug 6, 2026 | Aug 3, 2026 |
| 3 | Initial insider ownership | Aug 6, 2026 | Aug 3, 2026 |
| 8-K |
Current report
Material agreement, New debt, Regulation FD disclosure, Other events
|
Jul 14, 2026 | Jul 8, 2026 |
| 4 | Insider transaction | Jun 25, 2026 | Jun 23, 2026 |
| 4 | Insider transaction | Jun 25, 2026 | Jun 23, 2026 |
| 4 | Insider transaction | Jun 25, 2026 | Jun 23, 2026 |
| 4 | Insider transaction | Jun 25, 2026 | Jun 23, 2026 |
| 4 | Insider transaction | Jun 25, 2026 | Jun 23, 2026 |
| 4 | Insider transaction | Jun 25, 2026 | Jun 23, 2026 |
| 4 | Insider transaction | Jun 25, 2026 | Jun 23, 2026 |
| 8-K |
Current report
Officer or director change, Bylaw or fiscal year change, Shareholder vote results
|
Jun 25, 2026 | Jun 23, 2026 |
| S-8 | Employee stock plan registration | Jun 23, 2026 | — |
| 8-K |
Current report
Regulation FD disclosure, Other events
|
Jun 22, 2026 | Jun 17, 2026 |
| 10-Q | Quarterly report | May 13, 2026 | Mar 31, 2026 |
| 8-K |
Current report
Results of operations
|
May 13, 2026 | May 13, 2026 |
| 4 | Insider transaction | May 6, 2026 | May 4, 2026 |
| ARS | Annual report to shareholders | Apr 27, 2026 | Dec 31, 2025 |
| DEFA14A | Additional proxy material | Apr 27, 2026 | — |
| DEF 14A | Proxy statement | Apr 27, 2026 | Jun 23, 2026 |
| PRE 14A | Preliminary proxy statement | Apr 13, 2026 | Jun 23, 2026 |
| 8-K |
Current report
Results of operations
|
Mar 26, 2026 | Mar 26, 2026 |
| 10-K | Annual report | Mar 26, 2026 | Dec 31, 2025 |
| 4 | Insider transaction | Feb 9, 2026 | Feb 6, 2026 |
| 4 | Insider transaction | Feb 9, 2026 | Feb 6, 2026 |
| 4 | Insider transaction | Feb 5, 2026 | Feb 2, 2026 |
| 4 | Insider transaction | Feb 4, 2026 | Feb 2, 2026 |
| 8-K |
Current report
Officer or director change, Other events
|
Jan 30, 2026 | Jan 30, 2026 |
| 8-K |
Current report
Other events
|
Dec 19, 2025 | Dec 19, 2025 |
| 8-K |
Current report
Results of operations, Regulation FD disclosure
|
Nov 13, 2025 | Nov 13, 2025 |
| 10-Q | Quarterly report | Nov 13, 2025 | Sep 30, 2025 |
| 4 | Insider transaction | Nov 12, 2025 | Nov 7, 2025 |
| 4 | Insider transaction | Sep 3, 2025 | Aug 28, 2025 |
| 4 | Insider transaction | Sep 3, 2025 | Aug 28, 2025 |
| SCHEDULE 13G/A | Amended ownership over 5% (passive) | Aug 14, 2025 | — |
| S-8 | Employee stock plan registration | Aug 12, 2025 | — |
| 10-Q | Quarterly report | Aug 12, 2025 | Jun 30, 2025 |
| 8-K |
Current report
Results of operations, Regulation FD disclosure
|
Aug 12, 2025 | Aug 12, 2025 |
| 8-K |
Current report
Officer or director change, Shareholder vote results
|
Jun 18, 2025 | Jun 12, 2025 |
| 4 | Insider transaction | Jun 16, 2025 | Jun 12, 2025 |
| 4 | Insider transaction | Jun 16, 2025 | Jun 12, 2025 |
| 4 | Insider transaction | Jun 16, 2025 | Jun 12, 2025 |
| 4 | Insider transaction | Jun 16, 2025 | Jun 12, 2025 |
| 4 | Insider transaction | Jun 16, 2025 | Jun 12, 2025 |
| 4 | Insider transaction | Jun 16, 2025 | Jun 12, 2025 |
| 4 | Insider transaction | Jun 16, 2025 | Jun 12, 2025 |
| 4 | Insider transaction | Jun 16, 2025 | Jun 12, 2025 |
| 8-K |
Current report
Regulation FD disclosure, Other events
|
May 28, 2025 | May 28, 2025 |
| 8-K |
Current report
Results of operations
|
May 13, 2025 | May 13, 2025 |
| 10-Q | Quarterly report | May 13, 2025 | Mar 31, 2025 |
| 4 | Insider transaction | May 6, 2025 | May 2, 2025 |
| ARS | Annual report to shareholders | Apr 28, 2025 | Dec 31, 2024 |
| DEFA14A | Additional proxy material | Apr 28, 2025 | — |
| DEF 14A | Proxy statement | Apr 28, 2025 | Jun 12, 2025 |
| 8-K |
Current report
Officer or director change
|
Apr 28, 2025 | Apr 22, 2025 |
| SCHEDULE 13D/A | Amended ownership over 5% (active) | Mar 28, 2025 | — |
| 8-K |
Current report
Results of operations
|
Mar 27, 2025 | Mar 27, 2025 |
| 10-K | Annual report | Mar 27, 2025 | Dec 31, 2024 |
| 8-K |
Current report
Listing notice
|
Feb 28, 2025 | Feb 25, 2025 |
| 4 | Insider transaction | Feb 5, 2025 | Feb 3, 2025 |
| 4 | Insider transaction | Feb 5, 2025 | Feb 3, 2025 |
| 4 | Insider transaction | Feb 5, 2025 | Feb 3, 2025 |
| 4 | Insider transaction | Feb 5, 2025 | Feb 5, 2025 |
| 8-K |
Current report
Results of operations, Officer or director change, Regulation FD disclosure, Other events
|
Jan 10, 2025 | Jan 7, 2025 |
| SC 13G/A | Amended ownership over 5% (passive) | Nov 14, 2024 | — |
| 8-K |
Current report
Results of operations
|
Nov 14, 2024 | Nov 14, 2024 |
| 10-Q | Quarterly report | Nov 14, 2024 | Sep 30, 2024 |
| 4 | Insider transaction | Nov 12, 2024 | Nov 7, 2024 |
| 8-K |
Current report
Results of operations, Exit or restructuring costs, Regulation FD disclosure, Other events
|
Oct 29, 2024 | Oct 29, 2024 |
| 8-K |
Current report
Regulation FD disclosure
|
Sep 10, 2024 | Sep 9, 2024 |
| 4 | Insider transaction | Aug 29, 2024 | Aug 27, 2024 |
| 4 | Insider transaction | Aug 29, 2024 | Aug 27, 2024 |
| 4 | Insider transaction | Aug 29, 2024 | Aug 27, 2024 |
| 4 | Insider transaction | Aug 6, 2024 | Aug 2, 2024 |
| S-8 | Employee stock plan registration | Aug 5, 2024 | — |
| 10-Q | Quarterly report | Aug 5, 2024 | Jun 30, 2024 |
| 8-K |
Current report
Results of operations, Regulation FD disclosure
|
Aug 5, 2024 | Aug 5, 2024 |
| 8-K |
Current report
Officer or director change, Shareholder vote results
|
Jun 3, 2024 | May 29, 2024 |
| 4 | Insider transaction | May 30, 2024 | May 29, 2024 |
| 4 | Insider transaction | May 30, 2024 | May 29, 2024 |
| 4 | Insider transaction | May 30, 2024 | May 29, 2024 |
| 4 | Insider transaction | May 30, 2024 | May 29, 2024 |
| 4 | Insider transaction | May 30, 2024 | May 29, 2024 |
| 4 | Insider transaction | May 30, 2024 | May 29, 2024 |
| 4 | Insider transaction | May 30, 2024 | May 29, 2024 |
| 4 | Insider transaction | May 30, 2024 | May 29, 2024 |
| 8-K |
Current report
Results of operations
|
May 15, 2024 | May 15, 2024 |
| 10-Q | Quarterly report | May 15, 2024 | Mar 31, 2024 |
| ARS | Annual report to shareholders | Apr 16, 2024 | Dec 31, 2023 |
| DEFA14A | Additional proxy material | Apr 16, 2024 | — |
| DEF 14A | Proxy statement | Apr 16, 2024 | May 29, 2024 |
| 8-K |
Current report
Other events
|
Mar 29, 2024 | Mar 29, 2024 |
| EFFECT | Filing | Mar 22, 2024 | — |
| CORRESP | Letter to the SEC | Mar 20, 2024 | — |
| UPLOAD | Letter from the SEC | Mar 20, 2024 | — |
| S-3 | Shelf registration | Mar 15, 2024 | — |
| S-8 | Employee stock plan registration | Mar 15, 2024 | — |
| 10-K | Annual report | Mar 13, 2024 | Dec 31, 2023 |
| 8-K |
Current report
Results of operations
|
Mar 13, 2024 | Mar 13, 2024 |
| SC 13G | Ownership over 5% (passive) | Feb 14, 2024 | — |
| 8-K |
Current report
Officer or director change
|
Feb 9, 2024 | Feb 5, 2024 |
| 4 | Insider transaction | Feb 5, 2024 | Feb 1, 2024 |
| 4 | Insider transaction | Feb 5, 2024 | Feb 2, 2024 |
| 4 | Insider transaction | Feb 5, 2024 | Feb 1, 2024 |
| 4 | Insider transaction | Feb 5, 2024 | Feb 1, 2024 |
| 4 | Insider transaction | Feb 5, 2024 | Feb 1, 2024 |
| 4 | Insider transaction | Feb 5, 2024 | Feb 1, 2024 |
| 144 | Notice of proposed sale | Feb 5, 2024 | — |
| 8-K |
Current report
Regulation FD disclosure
|
Jan 8, 2024 | Jan 8, 2024 |
| 8-K |
Current report
Results of operations, Regulation FD disclosure, Other events
|
Jan 5, 2024 | Jan 5, 2024 |
| 4 | Insider transaction | Jan 4, 2024 | Jan 2, 2024 |
| 8-K |
Current report
Regulation FD disclosure, Other events
|
Jan 2, 2024 | Jan 2, 2024 |
| 4 | Insider transaction | Nov 15, 2023 | Nov 13, 2023 |
| 3 | Initial insider ownership | Nov 15, 2023 | Nov 6, 2023 |
| S-8 | Employee stock plan registration | Nov 13, 2023 | — |
| S-8 | Employee stock plan registration | Nov 13, 2023 | — |
| 8-K |
Current report
Results of operations
|
Nov 13, 2023 | Nov 13, 2023 |
| 10-Q | Quarterly report | Nov 13, 2023 | Sep 30, 2023 |
| 8-K |
Current report
Officer or director change, Other events
|
Nov 1, 2023 | Oct 30, 2023 |
| 8-K/A |
Amended current report
Bylaw or fiscal year change, Shareholder vote results
|
Oct 16, 2023 | Oct 5, 2023 |
| 4 | Insider transaction | Oct 10, 2023 | Oct 5, 2023 |
| 4 | Insider transaction | Oct 10, 2023 | Oct 5, 2023 |
| 4 | Insider transaction | Oct 10, 2023 | Oct 5, 2023 |
| 4 | Insider transaction | Oct 10, 2023 | Oct 5, 2023 |
| 4 | Insider transaction | Oct 10, 2023 | Oct 5, 2023 |
| 4 | Insider transaction | Oct 10, 2023 | Oct 5, 2023 |
| 4 | Insider transaction | Oct 10, 2023 | Oct 5, 2023 |
| 4 | Insider transaction | Oct 10, 2023 | Oct 5, 2023 |
| 8-K |
Current report
Officer or director change, Bylaw or fiscal year change, Shareholder vote results
|
Oct 10, 2023 | Oct 5, 2023 |
| 4 | Insider transaction | Sep 15, 2023 | Sep 13, 2023 |
| ARS | Annual report to shareholders | Sep 1, 2023 | Dec 31, 2022 |
| DEF 14A | Proxy statement | Sep 1, 2023 | Oct 5, 2023 |
| 4 | Insider transaction | Aug 30, 2023 | Aug 28, 2023 |
| 4 | Insider transaction | Aug 30, 2023 | Aug 28, 2023 |
| 4 | Insider transaction | Aug 30, 2023 | Aug 28, 2023 |
| 4 | Insider transaction | Aug 30, 2023 | Aug 28, 2023 |
| 144 | Notice of proposed sale | Aug 29, 2023 | — |
| PRE 14A | Preliminary proxy statement | Aug 22, 2023 | Oct 5, 2023 |
| S-8 | Employee stock plan registration | Aug 10, 2023 | — |
| 8-K |
Current report
Results of operations
|
Aug 10, 2023 | Aug 10, 2023 |
| 10-Q | Quarterly report | Aug 10, 2023 | Jun 30, 2023 |
| 4 | Insider transaction | Aug 3, 2023 | Aug 1, 2023 |
| 8-K |
Current report
Regulation FD disclosure, Other events
|
Jul 31, 2023 | Jul 31, 2023 |
| 3 | Initial insider ownership | Jul 24, 2023 | Jul 15, 2023 |
| 4 | Insider transaction | Jun 14, 2023 | Jun 12, 2023 |
| 8-K |
Current report
Officer or director change, Other events
|
Jun 14, 2023 | Jun 12, 2023 |
| 8-K |
Current report
Results of operations
|
May 11, 2023 | May 11, 2023 |
| 10-Q | Quarterly report | May 11, 2023 | Mar 31, 2023 |
| S-8 | Employee stock plan registration | Mar 30, 2023 | — |
| 8-K |
Current report
Results of operations
|
Mar 30, 2023 | Mar 30, 2023 |
| 10-K | Annual report | Mar 30, 2023 | Dec 31, 2022 |
| SC 13G/A | Amended ownership over 5% (passive) | Feb 14, 2023 | — |
| SC 13G/A | Amended ownership over 5% (passive) | Feb 14, 2023 | — |
| 4 | Insider transaction | Feb 6, 2023 | Feb 3, 2023 |
| 4 | Insider transaction | Feb 3, 2023 | Feb 1, 2023 |
| 4 | Insider transaction | Feb 3, 2023 | Feb 1, 2023 |
| 4 | Insider transaction | Feb 3, 2023 | Feb 1, 2023 |
| 4 | Insider transaction | Feb 3, 2023 | Feb 1, 2023 |
| 4 | Insider transaction | Feb 3, 2023 | Feb 1, 2023 |
| 8-K |
Current report
Officer or director change
|
Feb 1, 2023 | Jan 30, 2023 |
| SC 13D/A | Amended ownership over 5% (active) | Jan 20, 2023 | — |
| CT ORDER | Filing | Jan 19, 2023 | — |
| 8-K |
Current report
Results of operations, Regulation FD disclosure, Other events
|
Jan 9, 2023 | Jan 9, 2023 |
| 4 | Insider transaction | Jan 5, 2023 | Jan 3, 2023 |
| 4 | Insider transaction | Jan 5, 2023 | Jan 3, 2023 |
| D | Filing | Nov 15, 2022 | — |
| 3 | Initial insider ownership | Nov 14, 2022 | Nov 7, 2022 |
| SC 13D/A | Amended ownership over 5% (active) | Nov 14, 2022 | — |
| S-8 | Employee stock plan registration | Nov 14, 2022 | — |
| 8-K |
Current report
Results of operations
|
Nov 14, 2022 | Nov 14, 2022 |
| 10-Q | Quarterly report | Nov 14, 2022 | Sep 30, 2022 |
| 8-K |
Current report
Other events
|
Nov 8, 2022 | Nov 8, 2022 |
| SC 13G/A | Amended ownership over 5% (passive) | Oct 3, 2022 | — |
| 4 | Insider transaction | Sep 26, 2022 | Sep 22, 2022 |
| 8-K |
Current report
Material agreement, Unregistered share sale, Other events
|
Sep 22, 2022 | Sep 21, 2022 |
| 4 | Insider transaction | Sep 19, 2022 | Sep 15, 2022 |
| 4 | Insider transaction | Sep 19, 2022 | Sep 15, 2022 |
| 4 | Insider transaction | Sep 19, 2022 | Sep 15, 2022 |
| 4 | Insider transaction | Sep 19, 2022 | Sep 15, 2022 |
| 4 | Insider transaction | Sep 19, 2022 | Sep 15, 2022 |
| 4 | Insider transaction | Sep 19, 2022 | Sep 15, 2022 |
| 4 | Insider transaction | Sep 19, 2022 | Sep 15, 2022 |
| 8-K |
Current report
Officer or director change, Shareholder vote results
|
Sep 19, 2022 | Sep 15, 2022 |
| 4 | Insider transaction | Sep 14, 2022 | Sep 12, 2022 |
| 3 | Initial insider ownership | Sep 14, 2022 | Sep 12, 2022 |
| 8-K |
Current report
Other events
|
Sep 6, 2022 | Sep 6, 2022 |
| 4 | Insider transaction | Aug 30, 2022 | Aug 29, 2022 |
| 8-K |
Current report
Results of operations
|
Aug 10, 2022 | Aug 10, 2022 |
| 10-Q | Quarterly report | Aug 10, 2022 | Jun 30, 2022 |
| DEFA14A | Additional proxy material | Aug 5, 2022 | — |
| DEF 14A | Proxy statement | Aug 5, 2022 | Sep 15, 2022 |
| SC 13G | Ownership over 5% (passive) | Jul 8, 2022 | — |
| 8-K |
Current report
Officer or director change
|
Jul 1, 2022 | Jul 1, 2022 |
| 8-K |
Current report
Other events
|
Jun 27, 2022 | Jun 27, 2022 |
Showing 200 filings, the most recent 200. Main filings leave out insider and ownership forms such as Form 4; choose a type above to see them. Each form opens on SEC.gov. Older filings are on SEC EDGAR.
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Company profile
- Industry
- Pharmaceutical Preparations (SIC 2834)
- Listed as
- SPRO (Nasdaq)
- Fiscal year ends
- December 31
- Incorporated in
- DE
- Headquarters
- Cambridge, MA
- SEC filer status
- Non-accelerated filer, Smaller reporting company
- SEC CIK
- 1701108
- Former names
- Spero Therapeutics, LLC (until Mar 21, 2017)
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Source: SEC EDGAR filings. This is company-reported data, not investment advice.