American Superconductor Corporation
American Superconductor Corporation (AMSC) Stock Ownership
Institutional vs insider vs public ownership from 13F and float data — top holders, activity, and insider trades below.
SEC 13F · FMP · AMSC · as of Sep 30, 2025
Ownership Breakdown
297
Institutional Holders
▲ 49 vs Q2
$1.94B
Total Inst. Value
▲ $740.29M vs Q2
47.69M
Shares Outstanding
freeFloat 96.34%
32.70M
13F Shares Held
▼ 15,366 vs Q2
Institutional ownership = 13F shares ÷ total outstanding. Insider % = 100 − free float. Public % = free float − institution %. Data: FMP /symbol-positions-summary + /shares-float + SEC EDGAR.
Top Institutional Holders
AMSC largest shareholders · institutional ownership
Q3 2025 · SEC 13F
Showing top 10 holders
| Holder | Shares | % Owned | Weight | Value | Reported | Change |
|---|---|---|---|---|---|---|
BLACKROCK, INC. motors & generators | 3.63M | 9.34% | 9.34% | $215.54B | Nov 12, 2025 | ▲ 209.3K |
VANGUARD GROUP INC motors & generators | 2.95M | 7.59% | 7.59% | $175.19B | Nov 7, 2025 | ▲ 502.8K |
BAILLIE GIFFORD & CO motors & generators | 1.43M | 3.67% | 3.67% | $84.77B | Oct 31, 2025 | ▼ 25.3K |
DRIEHAUS CAPITAL MANAGEMENT LLC motors & generators | 1.22M | 3.14% | 3.14% | $72.39B | Nov 14, 2025 | ▲ 379.1K |
GOLDMAN SACHS GROUP INC motors & generators | 1.17M | 3.02% | 3.02% | $69.73B | Nov 14, 2025 | ▲ 145.1K |
STATE STREET CORP motors & generators | 1.14M | 2.92% | 2.92% | $67.46B | Nov 14, 2025 | ▲ 115.7K |
GEODE CAPITAL MANAGEMENT, LLC motors & generators | 1.07M | 2.75% | 2.75% | $63.55B | Nov 12, 2025 | ▲ 129.7K |
NUVEEN, LLC motors & generators | 826.2K | 2.13% | 2.13% | $49.07B | Nov 12, 2025 | ▼ 171.8K |
FULLER & THALER ASSET MANAGEMENT, INC. motors & generators | 809.9K | 2.08% | 2.08% | $48.10B | Nov 13, 2025 | NEW |
ATREIDES MANAGEMENT, LP motors & generators | 771.5K | 1.98% | 1.98% | $45.82B | Nov 14, 2025 | ▼ 333.0K |
Data from SEC Form 13F filings. Ownership bar normalised to largest holder. Change flags: isNew / isSoldOut / changeInSharesNumber (FMP extract-analytics/holder).
Institutional Activity
Q3 2025 vs prior quarter
Q3 2025
24
Increased
+3.93M shares4
New Positions
first time holders21
Decreased
−3.54M shares0
Sold Out
fully exitedNet shares change (top 50)
+381.7K
+3.93M / −3.54M
Net new holders
+7
4 new / 0 exited
Based on top 50 institutional holders by position size. Fields: isNew, isSoldOut, changeInSharesNumber (FMP extract-analytics/holder, limit=50).
Insider Buying vs Selling
AMSC insider trading · insider activity
Source: SEC Form 4
Insiders have been primarily selling shares recently. Selling may be driven by pre-scheduled Rule 10b5-1 plans rather than negative sentiment.
0
Buy transactions
1
Sell transactions
0.00
Buy/Sell ratio
$0M
Total disposed
Recent Insider Transactions
Showing 10 most recent · Common Stock only
| Name · Role | Date | Type | Shares | Price | Value | After Trans. | Filing |
|---|---|---|---|---|---|---|---|
Donnelly Terence Robert director | Apr 3, 2026 | Award | 2,665 | — | — | 2.7K | Form 4 ↗ |
OLIVER DAVID R JR director | Apr 3, 2026 | Award | 3,116 | — | — | 63.8K | Form 4 ↗ |
Littlefield Barbara G. director | Apr 3, 2026 | Award | 3,116 | — | — | 35.4K | Form 4 ↗ |
Klein Margaret D. director | Apr 3, 2026 | Award | 3,116 | — | — | 19.5K | Form 4 ↗ |
House Arthur H director | Apr 3, 2026 | Award | 3,116 | — | — | 51.8K | Form 4 ↗ |
Dambier Laura A. director | Apr 3, 2026 | Award | 3,116 | — | — | 19.0K | Form 4 ↗ |
OLIVER DAVID R JR director | Feb 24, 2026 | Sale | 200 | $34.10 | $6.8K | 60.7K | Form 4 ↗ |
OLIVER DAVID R JR director | Jun 18, 2019 | Purchase | 200 | $8.33 | $1.7K | 60.9K | Form 4 ↗ |
House Arthur H director | Aug 8, 2025 | Sale | 9,703 | $50.92 | $494.1K | 48.7K | Form 4 ↗ |
Klein Margaret D. director | Aug 4, 2022 | Purchase | 500 | $5.57 | $2.8K | 16.4K | Form 4 ↗ |
Source: /insider-trading/search (FMP stable). Buy/Sell direction: acquisitionOrDisposition A=Buy, D=Sell. RSU vesting (M-Exempt) excluded from sentiment bar. All data from SEC EDGAR public filings.
About institutional & insider ownership
American Superconductor Corporation (AMSC) is primarily owned by institutional investors, who hold approximately 68.6% of total shares outstanding. Company insiders own approximately 3.66%, while retail and public investors account for the remaining 27.78%.
The largest institutional shareholder of American Superconductor Corporation is BLACKROCK, INC., holding approximately 3.63 million shares — equal to 9.34% of outstanding shares — as of September 30, 2025.
A total of 297 institutional investors currently hold AMSC stock, with a combined institutional value of approximately $1.94 billion as of the most recent 13F filing period.
Frequently asked questions
AMSC ownershipAmerican Superconductor Corporation (AMSC) is primarily owned by institutional investors, who hold approximately 68.6% of shares. The largest shareholder is BLACKROCK, INC. with a 9.34% stake. Company insiders hold 3.66%. Data sourced from SEC Form 13F as of September 30, 2025.