---
schema_version: "secwatch.filing_event.v1"
accession: "0001193125-25-330930"
form_type: "8-K"
ticker: "AMSC"
cik: "0000880807"
company_name: "AMERICAN SUPERCONDUCTOR CORP /DE/"
filed_at: "2025-12-23T23:59:59+00:00"
generated_at: "2026-05-16T12:22:30.660716+00:00"
event_type: "other_material"
sentiment: "neutral"
materiality_score: 0.2
calibrated_materiality_score: 0.2
confidence: "medium"
source: SEC EDGAR
---

# AMSC files prospectus supplement for common stock resale by selling stockholders

## Summary
- Prospectus supplement filed Dec 23, 2025 under existing S-3 shelf registration.
- Shares to be sold from time to time by certain selling stockholders; no new share issuance by AMSC.
- Latham & Watkins legal opinion on share validity filed as Exhibit 5.1.

## SEC filing metadata
- accession: 0001193125-25-330930
- form_type: 8-K
- ticker: AMSC
- cik: 0000880807
- company_name: AMERICAN SUPERCONDUCTOR CORP /DE/
- filed_at: 2025-12-23T23:59:59+00:00
- event_type: other_material
- sentiment: neutral
- materiality_score: 0.2
- calibrated_materiality_score: 0.2
- confidence: medium
- sec_items: 8.01, 9.01
- EDGAR index: https://www.sec.gov/Archives/edgar/data/880807/000119312525330930/0001193125-25-330930-index.htm
- EDGAR primary document: https://www.sec.gov/Archives/edgar/data/880807/000119312525330930/d36453d8k.htm

## Machine-readable alternates
- HTML: https://secwatch.observer/filing/0001193125-25-330930
- JSON: https://secwatch.observer/filing/0001193125-25-330930.json
- Plain text: https://secwatch.observer/filing/0001193125-25-330930.txt

This AI-assisted summary is a reading aid. Review the linked SEC EDGAR filing before relying on any specific claim.