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 |
|---|---|---|---|
| 4 | Insider transaction | Aug 6, 2026 | Aug 3, 2026 |
| 3 | Initial insider ownership | Aug 6, 2026 | Aug 3, 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 |
| 4 | Insider transaction | May 6, 2026 | May 4, 2026 |
| 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 |
| 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 | — |
| 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 |
| 4 | Insider transaction | May 6, 2025 | May 2, 2025 |
| SCHEDULE 13D/A | Amended ownership over 5% (active) | Mar 28, 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 |
| SC 13G/A | Amended ownership over 5% (passive) | Nov 14, 2024 | — |
| 4 | Insider transaction | Nov 12, 2024 | Nov 7, 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 |
| 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 |
| SC 13G | Ownership over 5% (passive) | Feb 14, 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 | — |
| 4 | Insider transaction | Jan 4, 2024 | Jan 2, 2024 |
| 4 | Insider transaction | Nov 15, 2023 | Nov 13, 2023 |
| 3 | Initial insider ownership | Nov 15, 2023 | Nov 6, 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 |
| 4 | Insider transaction | Sep 15, 2023 | Sep 13, 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 | — |
| 4 | Insider transaction | Aug 3, 2023 | Aug 1, 2023 |
| 3 | Initial insider ownership | Jul 24, 2023 | Jul 15, 2023 |
| 4 | Insider transaction | Jun 14, 2023 | Jun 12, 2023 |
| 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 |
| SC 13D/A | Amended ownership over 5% (active) | Jan 20, 2023 | — |
| 4 | Insider transaction | Jan 5, 2023 | Jan 3, 2023 |
| 4 | Insider transaction | Jan 5, 2023 | Jan 3, 2023 |
| 3 | Initial insider ownership | Nov 14, 2022 | Nov 7, 2022 |
| SC 13D/A | Amended ownership over 5% (active) | Nov 14, 2022 | — |
| SC 13G/A | Amended ownership over 5% (passive) | Oct 3, 2022 | — |
| 4 | Insider transaction | Sep 26, 2022 | Sep 22, 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 |
| 4 | Insider transaction | Sep 14, 2022 | Sep 12, 2022 |
| 3 | Initial insider ownership | Sep 14, 2022 | Sep 12, 2022 |
| 4 | Insider transaction | Aug 30, 2022 | Aug 29, 2022 |
| SC 13G | Ownership over 5% (passive) | Jul 8, 2022 | — |
| 4 | Insider transaction | Apr 28, 2022 | Apr 26, 2022 |
| 4 | Insider transaction | Mar 31, 2022 | Mar 30, 2022 |
| 4 | Insider transaction | Mar 16, 2022 | Mar 14, 2022 |
| SC 13G/A | Amended ownership over 5% (passive) | Mar 9, 2022 | — |
| 4 | Insider transaction | Mar 2, 2022 | Feb 28, 2022 |
| 4 | Insider transaction | Feb 23, 2022 | Feb 18, 2022 |
| SC 13G/A | Amended ownership over 5% (passive) | Feb 14, 2022 | — |
| SC 13G/A | Amended ownership over 5% (passive) | Feb 14, 2022 | — |
| SC 13G/A | Amended ownership over 5% (passive) | Feb 3, 2022 | — |
| 4 | Insider transaction | Feb 3, 2022 | Feb 1, 2022 |
| 4 | Insider transaction | Feb 3, 2022 | Feb 1, 2022 |
| 4 | Insider transaction | Feb 3, 2022 | Feb 1, 2022 |
| 4 | Insider transaction | Feb 3, 2022 | Feb 1, 2022 |
| 4 | Insider transaction | Feb 3, 2022 | Feb 1, 2022 |
| 4 | Insider transaction | Feb 3, 2022 | Feb 1, 2022 |
| 4 | Insider transaction | Feb 1, 2022 | Jan 31, 2022 |
| 4 | Insider transaction | Jan 26, 2022 | Jan 24, 2022 |
| SC 13G/A | Amended ownership over 5% (passive) | Jan 25, 2022 | — |
| 4 | Insider transaction | Jan 20, 2022 | Jan 18, 2022 |
| 4 | Insider transaction | Jan 12, 2022 | Jan 10, 2022 |
| 4 | Insider transaction | Jan 7, 2022 | Jan 5, 2022 |
| 4 | Insider transaction | Jan 7, 2022 | Jan 5, 2022 |
| 4 | Insider transaction | Jan 7, 2022 | Jan 5, 2022 |
| 4 | Insider transaction | Jan 3, 2022 | Dec 29, 2021 |
| 4 | Insider transaction | Dec 29, 2021 | Dec 27, 2021 |
| 4 | Insider transaction | Nov 12, 2021 | Nov 11, 2021 |
| 4 | Insider transaction | Nov 2, 2021 | Oct 29, 2021 |
| 3 | Initial insider ownership | Oct 14, 2021 | Oct 11, 2021 |
| 4 | Insider transaction | Oct 4, 2021 | Sep 30, 2021 |
| SC 13D/A | Amended ownership over 5% (active) | Sep 16, 2021 | — |
| 4 | Insider transaction | Sep 15, 2021 | Sep 13, 2021 |
| 4 | Insider transaction | Sep 10, 2021 | Sep 9, 2021 |
| 4 | Insider transaction | Sep 1, 2021 | Aug 30, 2021 |
| 4 | Insider transaction | Aug 30, 2021 | Aug 26, 2021 |
| 4 | Insider transaction | Aug 30, 2021 | Aug 26, 2021 |
| 4 | Insider transaction | Aug 30, 2021 | Aug 26, 2021 |
| 4 | Insider transaction | Aug 30, 2021 | Aug 26, 2021 |
| 4 | Insider transaction | Aug 30, 2021 | Aug 26, 2021 |
| 4 | Insider transaction | Aug 30, 2021 | Aug 26, 2021 |
| 4 | Insider transaction | Aug 27, 2021 | Aug 26, 2021 |
| 4 | Insider transaction | Aug 24, 2021 | Aug 20, 2021 |
| 4 | Insider transaction | Aug 18, 2021 | Aug 17, 2021 |
| 4 | Insider transaction | Aug 18, 2021 | Aug 17, 2021 |
| 4 | Insider transaction | Aug 18, 2021 | Aug 17, 2021 |
| 4 | Insider transaction | Aug 18, 2021 | Aug 17, 2021 |
| 4 | Insider transaction | Aug 18, 2021 | Aug 17, 2021 |
| 4 | Insider transaction | Aug 18, 2021 | Aug 17, 2021 |
| 4 | Insider transaction | Aug 18, 2021 | Aug 17, 2021 |
| SC 13G | Ownership over 5% (passive) | Jul 9, 2021 | — |
| SC 13D/A | Amended ownership over 5% (active) | Feb 16, 2021 | — |
| SC 13G/A | Amended ownership over 5% (passive) | Feb 16, 2021 | — |
| SC 13G/A | Amended ownership over 5% (passive) | Feb 16, 2021 | — |
| SC 13G/A | Amended ownership over 5% (passive) | Feb 10, 2021 | — |
| 4 | Insider transaction | Feb 10, 2021 | Feb 8, 2021 |
| 4 | Insider transaction | Feb 4, 2021 | Feb 1, 2021 |
| 4 | Insider transaction | Feb 3, 2021 | Feb 1, 2021 |
| 4 | Insider transaction | Feb 3, 2021 | Feb 1, 2021 |
| 4 | Insider transaction | Feb 3, 2021 | Feb 1, 2021 |
| 4 | Insider transaction | Feb 3, 2021 | Feb 1, 2021 |
| SC 13G | Ownership over 5% (passive) | Feb 2, 2021 | — |
| SC 13G/A | Amended ownership over 5% (passive) | Feb 2, 2021 | — |
| 4 | Insider transaction | Jan 6, 2021 | Jan 4, 2021 |
| 4 | Insider transaction | Jan 6, 2021 | Jan 4, 2021 |
| 4 | Insider transaction | Jan 6, 2021 | Jan 4, 2021 |
| 4 | Insider transaction | Jan 6, 2021 | Jan 4, 2021 |
| 4 | Insider transaction | Jan 5, 2021 | Jan 4, 2021 |
| 3 | Initial insider ownership | Jan 5, 2021 | Jan 4, 2021 |
| 4 | Insider transaction | Dec 18, 2020 | Dec 16, 2020 |
| 4 | Insider transaction | Dec 18, 2020 | Dec 16, 2020 |
| SC 13D/A | Amended ownership over 5% (active) | Dec 7, 2020 | — |
| 4 | Insider transaction | Dec 2, 2020 | Dec 2, 2020 |
| 3 | Initial insider ownership | Dec 2, 2020 | Dec 2, 2020 |
| 4 | Insider transaction | Nov 10, 2020 | Nov 9, 2020 |
| 4 | Insider transaction | Nov 6, 2020 | Nov 4, 2020 |
| 4 | Insider transaction | Nov 5, 2020 | Nov 3, 2020 |
| 4 | Insider transaction | Oct 27, 2020 | Oct 27, 2020 |
| 4 | Insider transaction | Oct 27, 2020 | Oct 27, 2020 |
| 4 | Insider transaction | Oct 27, 2020 | Oct 27, 2020 |
| 4 | Insider transaction | Oct 27, 2020 | Oct 27, 2020 |
| 4 | Insider transaction | Oct 27, 2020 | Oct 27, 2020 |
| 4 | Insider transaction | Oct 27, 2020 | Oct 23, 2020 |
| 4 | Insider transaction | Oct 27, 2020 | Oct 27, 2020 |
| 4 | Insider transaction | Oct 27, 2020 | Oct 27, 2020 |
| 4 | Insider transaction | Oct 15, 2020 | Oct 13, 2020 |
| SC 13G/A | Amended ownership over 5% (passive) | Sep 23, 2020 | — |
| 3 | Initial insider ownership | Sep 22, 2020 | Sep 11, 2020 |
| 4 | Insider transaction | Sep 10, 2020 | Sep 8, 2020 |
| 4 | Insider transaction | Jul 9, 2020 | Jul 7, 2020 |
| 4 | Insider transaction | Jun 29, 2020 | Jun 22, 2020 |
| 4 | Insider transaction | Jun 23, 2020 | Jun 23, 2020 |
| SC 13D/A | Amended ownership over 5% (active) | Jun 4, 2020 | — |
| 3 | Initial insider ownership | Apr 23, 2020 | Apr 16, 2020 |
| SC 13G/A | Amended ownership over 5% (passive) | Feb 18, 2020 | — |
| SC 13D/A | Amended ownership over 5% (active) | Feb 14, 2020 | — |
| SC 13G/A | Amended ownership over 5% (passive) | Feb 14, 2020 | — |
| SC 13G/A | Amended ownership over 5% (passive) | Feb 4, 2020 | — |
| 4 | Insider transaction | Feb 3, 2020 | Feb 3, 2020 |
| 4 | Insider transaction | Feb 3, 2020 | Feb 3, 2020 |
| 4 | Insider transaction | Feb 3, 2020 | Feb 3, 2020 |
| 4 | Insider transaction | Feb 3, 2020 | Feb 3, 2020 |
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.
New to this? Read What Are SEC Filings? 10-K, 10-Q, 8-K and Other Forms Explained.
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)
Other Pharmaceutical Preparations companies
- ELI LILLY & Co LLY
- Johnson & Johnson JNJ
- AbbVie Inc. ABBV
- Merck & Co., Inc. MRK
- Novartis AG NVS
- Astrazeneca PLC AZN
- Abbott Laboratories ABT
- Novo Nordisk A S NVO
Source: SEC EDGAR filings. This is company-reported data, not investment advice.