CSTM · Insider trading · 13F holders · Congress trades
Constellium SE (CSTM)
Who is buying and selling CSTM: company insiders on SEC Form 4, hedge funds and superinvestors on Form 13F, and members of Congress under the STOCK Act. Every figure links to the filing or page it comes from.
- 13F filers holding
- 19
- Insider buys, 90 days
- $41K
- Insider sales, 90 days
- $0
- Congress trades, 12 months
- 1
CSTM at a glance
- Between Aug 1, 2026 and Oct 29, 2026, 1 CSTM insider filed 1 open-market purchase worth $41K on SEC Form 4.
- 19 13F filers hold CSTM among their 50 largest positions, worth $451.8M combined. The biggest bets by portfolio weight are Brightline Capital Management, LLC (13.3%), Mountaineer Partners Management, LLC (11.6%) and Beaconlight Capital, LLC (10.9%). In their latest 13Fs, 1 manager opened a new position and 1 added to one.
- Members of Congress have disclosed 1 CSTM trade since 2015, 0 purchases and 1 sale in the past year; the latest was Thomas MacArthur (R-NJ), selling $1K–15K on May 27, 2015.
- CSTM last closed at $24.02 on Oct 29, 2026.
CSTM insider trading
Between Aug 1, 2026 and Oct 29, 2026, 1 CSTM insider filed 1 open-market purchase worth $41K on SEC Form 4.
| Filed | Insider | Role | Trade | Shares | Price | Value | Form 4 |
|---|---|---|---|---|---|---|---|
| Aug 3, 2026 | Deslarzes Jean-Christophe | Director | Buy | 1,490 | $27.24 | $41K | SEC |
Who owns CSTM? Hedge funds and superinvestors
19 13F filers hold CSTM among their 50 largest positions, worth $451.8M combined. The biggest bets by portfolio weight are Brightline Capital Management, LLC (13.3%), Mountaineer Partners Management, LLC (11.6%) and Beaconlight Capital, LLC (10.9%). In their latest 13Fs, 1 manager opened a new position and 1 added to one.
| Manager | % of portfolio | Value | Shares | Last quarter | 13F |
|---|---|---|---|---|---|
| Kinetic Partners Management, LPHedge fund | 1.9% | $81.0M | 2,542,400 | +93.7% shares | Q2 2026 |
| Encompass Capital Advisors LLCHedge fund | 3.3% | $77.2M | 2,421,349 | -2.3% shares | Q2 2026 |
| Brightline Capital Management, LLCHedge fund | 13.3% | $61.3M | 1,923,000 | +4.1% shares | Q2 2026 |
| Scopus Asset Management, L.P.Hedge fund | 1.3% | $55.2M | 1,731,708 | +3.0% shares | Q2 2026 |
| Senator Investment Group LPHedge fund | 1.3% | $34.5M | 1,083,489 | — | Q2 2026 |
| Beaconlight Capital, LLCHedge fund | 10.9% | $24.9M | 779,899 | -33.4% shares | Q2 2026 |
| Penn Capital Management Company, LLCInstitutional asset manager | 1.5% | $23.9M | 749,645 | -11.3% shares | Q2 2026 |
| Bayberry Capital Partners LPHedge fund | 7.2% | $20.9M | 655,000 | -25.1% shares | Q2 2026 |
| Mountaineer Partners Management, LLCHedge fund | 11.6% | $15.4M | 482,130 | -26.8% shares | Q2 2026 |
| Occudo Quantitative Strategies LPHedge fund | 0.7% | $13.3M | 416,403 | — | Q2 2026 |
| Beacon Investment Advisors LLCWealth manager | 3.3% | $10.4M | 326,719 | -0.1% shares | Q2 2026 |
| Kailix Advisors LLCWealth manager | 8.6% | $8.9M | 278,200 | -43.7% shares | Q2 2026 |
| Cvfg LLCWealth manager | 0.9% | $8.5M | 266,220 | -2.6% shares | Q2 2026 |
| Soapstone Management L.P.Hedge fund | 4.6% | $6.4M | 200,000 | -75.0% shares | Q2 2026 |
| Rockingstone Advisors LLCWealth manager | 1.7% | $4.1M | 170,710 | -0.6% shares | Q3 2026 |
| Ionic Capital Management LLCHedge fund | 3.6% | $3.5M | 109,822 | -38.2% shares | Q2 2026 |
| Eddie Patel IncWealth manager | 1.0% | $1.7M | 53,958 | — | Q2 2026 |
| Lawson Kroeker Investment Management Inc/neAsset manager | 0.2% | $608K | 25,120 | +0.0% shares | Q3 2026 |
| Semanteon Capital Management, LPHedge fund | 1.1% | $233K | 7,299 | New | Q2 2026 |
Each manager counts with its latest 13F (Q3 2026: 2, Q2 2026: 17). Screen CSTM in the grand portfolio →
CSTM stock trades by members of Congress
Members of Congress have disclosed 1 CSTM trade since 2015, 0 purchases and 1 sale in the past year; the latest was Thomas MacArthur (R-NJ), selling $1K–15K on May 27, 2015.
| Filed | Member | Trade | Amount | Traded | Since |
|---|---|---|---|---|---|
| Jun 7, 2015 | Thomas MacArthurR-NJ · House | Sale | $1K–15K | May 27, 2015 | +67.5% |
CSTM questions and answers
Are insiders buying CSTM stock?
Between Aug 1, 2026 and Oct 29, 2026, 1 CSTM insider filed 1 open-market purchase worth $41K on SEC Form 4.
Which hedge funds own CSTM?
19 13F filers hold CSTM among their 50 largest positions, worth $451.8M combined. The biggest bets by portfolio weight are Brightline Capital Management, LLC (13.3%), Mountaineer Partners Management, LLC (11.6%) and Beaconlight Capital, LLC (10.9%). In their latest 13Fs, 1 manager opened a new position and 1 added to one.
Has Congress traded CSTM?
Members of Congress have disclosed 1 CSTM trade since 2015, 0 purchases and 1 sale in the past year; the latest was Thomas MacArthur (R-NJ), selling $1K–15K on May 27, 2015.
Who is the largest holder of CSTM?
Among 13F filers, Kinetic Partners Management, LP reports the largest CSTM position, $81.0M (2,542,400 shares) in its Q2 2026 13F. The biggest bet by portfolio weight is Brightline Capital Management, LLC's: 13.3% of its portfolio.
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