American Superconductor Corp /DE/ SEC filings AMSC
American Superconductor Corp /DE/ has 1,003 filings in SEC EDGAR's recent list, going back to Jan 31, 2008. Its latest annual report, Form ARS, was filed on Jun 18, 2026 for the period ended Mar 31, 2026. The latest quarterly report (Form 10-Q) was filed on Nov 4, 2026, covering the quarter ended Sep 30, 2026. The most recent current report (Form 8-K) was filed on Nov 4, 2026 (results of operations). The company's fiscal year ends on March 31.
| Form | Description | Filed | Period |
|---|---|---|---|
| 4 | Insider transaction | Sep 21, 2026 | Sep 18, 2026 |
| SCHEDULE 13G/A | Amended ownership over 5% (passive) | Jul 31, 2026 | — |
| 4 | Insider transaction | Jun 12, 2026 | Jun 11, 2026 |
| 144 | Notice of proposed sale | Jun 11, 2026 | — |
| 4 | Insider transaction | Jun 11, 2026 | Jun 11, 2026 |
| 4 | Insider transaction | Jun 11, 2026 | Jun 11, 2026 |
| 144 | Notice of proposed sale | Jun 11, 2026 | — |
| 4 | Insider transaction | Jun 10, 2026 | Jun 8, 2026 |
| 4 | Insider transaction | Jun 10, 2026 | Jun 8, 2026 |
| 144 | Notice of proposed sale | Jun 10, 2026 | — |
| 144 | Notice of proposed sale | Jun 8, 2026 | — |
| 144 | Notice of proposed sale | Jun 8, 2026 | — |
| 144 | Notice of proposed sale | Jun 3, 2026 | — |
| 144 | Notice of proposed sale | Jun 3, 2026 | — |
| 4 | Insider transaction | Jun 3, 2026 | Jun 1, 2026 |
| 4 | Insider transaction | Jun 3, 2026 | Jun 1, 2026 |
| 144 | Notice of proposed sale | Jun 2, 2026 | — |
| 144 | Notice of proposed sale | Jun 2, 2026 | — |
| SCHEDULE 13G | Ownership over 5% (passive) | Apr 29, 2026 | — |
| 4 | Insider transaction | Apr 7, 2026 | Apr 3, 2026 |
| 4 | Insider transaction | Apr 7, 2026 | Apr 3, 2026 |
| 4 | Insider transaction | Apr 7, 2026 | Apr 3, 2026 |
| 4 | Insider transaction | Apr 7, 2026 | Apr 3, 2026 |
| 4 | Insider transaction | Apr 7, 2026 | Apr 3, 2026 |
| 4 | Insider transaction | Apr 7, 2026 | Apr 3, 2026 |
| SCHEDULE 13G/A | Amended ownership over 5% (passive) | Mar 26, 2026 | — |
| 4 | Insider transaction | Feb 26, 2026 | Feb 24, 2026 |
| SCHEDULE 13G/A | Amended ownership over 5% (passive) | Jan 30, 2026 | — |
| 4 | Insider transaction | Nov 13, 2025 | Jun 18, 2019 |
| 144 | Notice of proposed sale | Aug 8, 2025 | — |
| 4 | Insider transaction | Aug 8, 2025 | Aug 6, 2025 |
| 4 | Insider transaction | Aug 6, 2025 | Aug 4, 2022 |
| 4 | Insider transaction | Aug 6, 2025 | Aug 4, 2025 |
| 4 | Insider transaction | Aug 6, 2025 | Aug 4, 2025 |
| 144 | Notice of proposed sale | Aug 4, 2025 | — |
| 144 | Notice of proposed sale | Aug 4, 2025 | — |
| 4 | Insider transaction | Jun 12, 2025 | Jun 11, 2025 |
| 4 | Insider transaction | Jun 12, 2025 | Jun 11, 2025 |
| 144 | Notice of proposed sale | Jun 11, 2025 | — |
| 144 | Notice of proposed sale | Jun 11, 2025 | — |
| 4 | Insider transaction | Jun 9, 2025 | Jun 6, 2025 |
| 4 | Insider transaction | Jun 9, 2025 | Jun 6, 2025 |
| 144 | Notice of proposed sale | Jun 6, 2025 | — |
| 144 | Notice of proposed sale | Jun 6, 2025 | — |
| 4 | Insider transaction | May 29, 2025 | May 27, 2025 |
| 4 | Insider transaction | May 29, 2025 | May 27, 2025 |
| 4 | Insider transaction | May 29, 2025 | May 27, 2025 |
| 3 | Initial insider ownership | May 29, 2025 | May 27, 2025 |
| 144 | Notice of proposed sale | May 27, 2025 | — |
| 144 | Notice of proposed sale | May 27, 2025 | — |
| 4 | Insider transaction | May 22, 2025 | May 20, 2025 |
| 4 | Insider transaction | May 22, 2025 | May 20, 2025 |
| 144 | Notice of proposed sale | May 20, 2025 | — |
| 144 | Notice of proposed sale | May 20, 2025 | — |
| 4 | Insider transaction | May 19, 2025 | May 15, 2025 |
| 4 | Insider transaction | May 19, 2025 | May 15, 2025 |
| SCHEDULE 13G/A | Amended ownership over 5% (passive) | Apr 17, 2025 | — |
| 4 | Insider transaction | Apr 4, 2025 | Apr 3, 2025 |
| 4 | Insider transaction | Apr 4, 2025 | Apr 3, 2025 |
| 4 | Insider transaction | Apr 4, 2025 | Apr 3, 2025 |
| 4 | Insider transaction | Apr 4, 2025 | Apr 3, 2025 |
| 4 | Insider transaction | Apr 4, 2025 | Apr 3, 2025 |
| SCHEDULE 13G/A | Amended ownership over 5% (passive) | Feb 12, 2025 | — |
| SCHEDULE 13G/A | Amended ownership over 5% (passive) | Feb 5, 2025 | — |
| SC 13G/A | Amended ownership over 5% (passive) | Nov 12, 2024 | — |
| SC 13G | Ownership over 5% (passive) | Nov 8, 2024 | — |
| 4 | Insider transaction | Nov 6, 2024 | Nov 4, 2024 |
| 144 | Notice of proposed sale | Nov 5, 2024 | — |
| SC 13G | Ownership over 5% (passive) | Nov 4, 2024 | — |
| SCHEDULE 13G/A | Amended ownership over 5% (passive) | Nov 4, 2024 | — |
| SC 13G | Ownership over 5% (passive) | Oct 22, 2024 | — |
| 4 | Insider transaction | Oct 1, 2024 | Sep 30, 2024 |
| 4 | Insider transaction | Sep 30, 2024 | Sep 26, 2024 |
| SC 13G/A | Amended ownership over 5% (passive) | Aug 9, 2024 | — |
| 4 | Insider transaction | Jun 12, 2024 | Jun 11, 2024 |
| 4 | Insider transaction | Jun 12, 2024 | Jun 11, 2024 |
| 144 | Notice of proposed sale | Jun 11, 2024 | — |
| 144 | Notice of proposed sale | Jun 11, 2024 | — |
| 4 | Insider transaction | May 23, 2024 | May 21, 2024 |
| 4 | Insider transaction | May 23, 2024 | May 21, 2024 |
| 144 | Notice of proposed sale | May 21, 2024 | — |
| 144 | Notice of proposed sale | May 21, 2024 | — |
| 4 | Insider transaction | Apr 4, 2024 | Apr 3, 2024 |
| 4 | Insider transaction | Apr 4, 2024 | Apr 3, 2024 |
| 4 | Insider transaction | Apr 4, 2024 | Apr 3, 2024 |
| 4 | Insider transaction | Apr 4, 2024 | Apr 3, 2024 |
| 4 | Insider transaction | Apr 4, 2024 | Apr 3, 2024 |
| SC 13G/A | Amended ownership over 5% (passive) | Feb 14, 2024 | — |
| SC 13G/A | Amended ownership over 5% (passive) | Jan 30, 2024 | — |
| SC 13G/A | Amended ownership over 5% (passive) | Jan 30, 2024 | — |
| SC 13G/A | Amended ownership over 5% (passive) | Jul 5, 2023 | — |
| 4 | Insider transaction | Jun 23, 2023 | Jun 21, 2023 |
| 4 | Insider transaction | Jun 23, 2023 | Jun 21, 2023 |
| 144 | Notice of proposed sale | Jun 22, 2023 | — |
| 144 | Notice of proposed sale | Jun 22, 2023 | — |
| 144 | Notice of proposed sale | Jun 21, 2023 | — |
| 144 | Notice of proposed sale | Jun 21, 2023 | — |
| 4 | Insider transaction | Jun 20, 2023 | Jun 15, 2023 |
| 4 | Insider transaction | Jun 20, 2023 | Jun 15, 2023 |
| 4 | Insider transaction | Apr 7, 2023 | Apr 5, 2023 |
| 4 | Insider transaction | Apr 7, 2023 | Apr 5, 2023 |
| 4 | Insider transaction | Apr 7, 2023 | Apr 5, 2023 |
| 4 | Insider transaction | Apr 7, 2023 | Apr 5, 2023 |
| 4 | Insider transaction | Apr 7, 2023 | Apr 5, 2023 |
| SC 13G | Ownership over 5% (passive) | Feb 14, 2023 | — |
| SC 13G/A | Amended ownership over 5% (passive) | Feb 8, 2023 | — |
| SC 13G | Ownership over 5% (passive) | Jan 31, 2023 | — |
| SC 13G/A | Amended ownership over 5% (passive) | Jan 19, 2023 | — |
| 4 | Insider transaction | Dec 19, 2022 | Dec 16, 2022 |
| 4 | Insider transaction | Dec 19, 2022 | Dec 16, 2022 |
| 4 | Insider transaction | Dec 13, 2022 | Dec 12, 2022 |
| 4 | Insider transaction | Nov 2, 2022 | Oct 31, 2022 |
| 4 | Insider transaction | Oct 21, 2022 | Oct 19, 2022 |
| SC 13G | Ownership over 5% (passive) | Jul 8, 2022 | — |
| 4 | Insider transaction | Jun 14, 2022 | Jun 10, 2022 |
| 4 | Insider transaction | Jun 14, 2022 | Jun 10, 2022 |
| 3 | Initial insider ownership | Jun 13, 2022 | Jun 10, 2022 |
| 3 | Initial insider ownership | Jun 13, 2022 | Jun 10, 2022 |
| 4 | Insider transaction | Jun 13, 2022 | Jun 10, 2022 |
| 4 | Insider transaction | Jun 13, 2022 | Jun 10, 2022 |
| 4 | Insider transaction | Jun 13, 2022 | Jun 10, 2022 |
| 4 | Insider transaction | Jun 2, 2022 | May 31, 2022 |
| 4 | Insider transaction | Jun 2, 2022 | May 31, 2022 |
| 4 | Insider transaction | Apr 6, 2022 | Apr 5, 2022 |
| 4 | Insider transaction | Apr 6, 2022 | Apr 5, 2022 |
| 4 | Insider transaction | Apr 6, 2022 | Apr 5, 2022 |
| 4 | Insider transaction | Apr 6, 2022 | Apr 5, 2022 |
| SC 13G | Ownership over 5% (passive) | Feb 14, 2022 | — |
| SC 13G/A | Amended ownership over 5% (passive) | Feb 9, 2022 | — |
| SC 13G/A | Amended ownership over 5% (passive) | Feb 1, 2022 | — |
| SC 13G | Ownership over 5% (passive) | Jan 18, 2022 | — |
| 4 | Insider transaction | Dec 13, 2021 | Dec 10, 2021 |
| 4 | Insider transaction | Dec 9, 2021 | Dec 8, 2021 |
| 4 | Insider transaction | Nov 2, 2021 | Nov 1, 2021 |
| 4 | Insider transaction | Nov 2, 2021 | Nov 1, 2021 |
| 4 | Insider transaction | Aug 6, 2021 | Aug 5, 2021 |
| 4 | Insider transaction | Aug 6, 2021 | Aug 5, 2021 |
| 4 | Insider transaction | Jul 6, 2021 | Jul 1, 2021 |
| 4 | Insider transaction | Jul 6, 2021 | Jul 1, 2021 |
| 4 | Insider transaction | May 24, 2021 | May 20, 2021 |
| 4 | Insider transaction | May 24, 2021 | May 20, 2021 |
| 4 | Insider transaction | Apr 7, 2021 | Apr 5, 2021 |
| 4 | Insider transaction | Apr 7, 2021 | Apr 5, 2021 |
| 4 | Insider transaction | Apr 7, 2021 | Apr 5, 2021 |
| 4 | Insider transaction | Apr 7, 2021 | Apr 5, 2021 |
| SC 13G | Ownership over 5% (passive) | Feb 16, 2021 | — |
| SC 13G/A | Amended ownership over 5% (passive) | Feb 10, 2021 | — |
| SC 13G/A | Amended ownership over 5% (passive) | Jan 29, 2021 | — |
| 4 | Insider transaction | Jan 22, 2021 | Jan 21, 2021 |
| SC 13G/A | Amended ownership over 5% (passive) | Jan 8, 2021 | — |
| 4 | Insider transaction | Nov 30, 2020 | Nov 25, 2020 |
| 4 | Insider transaction | Nov 2, 2020 | Oct 31, 2020 |
| 4 | Insider transaction | Nov 2, 2020 | Oct 31, 2020 |
| 4 | Insider transaction | Jul 29, 2020 | Jul 27, 2020 |
| 4 | Insider transaction | Jul 29, 2020 | Jul 27, 2020 |
| 4 | Insider transaction | Jun 30, 2020 | Jun 28, 2020 |
| 4 | Insider transaction | Jun 30, 2020 | Jun 28, 2020 |
| SC 13G/A | Amended ownership over 5% (passive) | Jun 19, 2020 | — |
| 4 | Insider transaction | Jun 4, 2020 | Jun 2, 2020 |
| 4 | Insider transaction | Jun 4, 2020 | Jun 2, 2020 |
| 4 | Insider transaction | May 26, 2020 | May 21, 2020 |
| 4 | Insider transaction | May 26, 2020 | May 21, 2020 |
| 4 | Insider transaction | Apr 7, 2020 | Apr 3, 2020 |
| 4 | Insider transaction | Apr 7, 2020 | Apr 3, 2020 |
| 4 | Insider transaction | Apr 7, 2020 | Apr 3, 2020 |
| 4 | Insider transaction | Apr 7, 2020 | Apr 3, 2020 |
| SC 13G/A | Amended ownership over 5% (passive) | Feb 13, 2020 | — |
| SC 13G/A | Amended ownership over 5% (passive) | Feb 12, 2020 | — |
| SC 13G | Ownership over 5% (passive) | Feb 12, 2020 | — |
| SC 13G | Ownership over 5% (passive) | Feb 7, 2020 | — |
| SC 13G/A | Amended ownership over 5% (passive) | Feb 4, 2020 | — |
| SC 13G | Ownership over 5% (passive) | Jan 27, 2020 | — |
| 4 | Insider transaction | Dec 23, 2019 | Dec 19, 2019 |
| 4 | Insider transaction | Nov 7, 2019 | Nov 5, 2019 |
| 4 | Insider transaction | Nov 7, 2019 | Nov 5, 2019 |
| 4 | Insider transaction | Nov 4, 2019 | Oct 31, 2019 |
| 4 | Insider transaction | Nov 4, 2019 | Oct 31, 2019 |
| 4 | Insider transaction | Jul 30, 2019 | Jul 27, 2019 |
| 4 | Insider transaction | Jul 30, 2019 | Jul 27, 2019 |
| 4 | Insider transaction | Jul 2, 2019 | Jun 28, 2019 |
| 4 | Insider transaction | Jul 2, 2019 | Jun 28, 2019 |
| SC 13G | Ownership over 5% (passive) | Jun 24, 2019 | — |
| 4 | Insider transaction | May 29, 2019 | May 24, 2019 |
| 3 | Initial insider ownership | May 29, 2019 | May 21, 2019 |
| 4 | Insider transaction | May 24, 2019 | May 24, 2019 |
| 4 | Insider transaction | May 14, 2019 | May 12, 2019 |
| 4 | Insider transaction | Apr 4, 2019 | Apr 3, 2019 |
| 4 | Insider transaction | Apr 4, 2019 | Apr 3, 2019 |
| 4 | Insider transaction | Apr 4, 2019 | Apr 3, 2019 |
| 4 | Insider transaction | Apr 4, 2019 | Apr 3, 2019 |
| SC 13G | Ownership over 5% (passive) | Feb 14, 2019 | — |
| SC 13G/A | Amended ownership over 5% (passive) | Feb 13, 2019 | — |
| SC 13G/A | Amended ownership over 5% (passive) | Feb 13, 2019 | — |
| SC 13G/A | Amended ownership over 5% (passive) | Feb 8, 2019 | — |
| SC 13G | Ownership over 5% (passive) | Feb 8, 2019 | — |
| 4 | Insider transaction | Jan 2, 2019 | Dec 28, 2018 |
| 4 | Insider transaction | Dec 11, 2018 | Dec 7, 2018 |
| 4 | Insider transaction | Nov 13, 2018 | Nov 8, 2018 |
| 4 | Insider transaction | Nov 13, 2018 | Nov 8, 2018 |
| 4 | Insider transaction | Nov 5, 2018 | Nov 1, 2018 |
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
- Motors & Generators (SIC 3621)
- Listed as
- AMSC (Nasdaq)
- Fiscal year ends
- March 31
- Incorporated in
- DE
- Headquarters
- Devens, MA
- SEC filer status
- Large accelerated filer
- SEC CIK
- 880807
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Source: SEC EDGAR filings. This is company-reported data, not investment advice.