Mountaineer Partners Management, LLC reported 10 positions worth $127.97M for the quarter ended Jun 30, 2026, down 34.9% on the prior quarter. It opened 1 new position, added to 1, trimmed 8 and exited 6. Its largest holding is Century Aluminum Co at 18.1% of the portfolio.
Reported 13F market value at each quarter end. A change mixes trading with price moves in the positions held.
Dollar value of shares bought and sold each quarter, at that quarter’s price. It counts trading only, not price changes.
How many positions were opened, added to, trimmed or closed each quarter.
Share of reported value in each sector at every quarter end.
| Holding | Change | Change % | Trade Value | Weight |
|---|---|---|---|---|
| HBM Hudbay Minerals Inc. | -706.0K | -100.0% | $14.76M | Exited |
| FCX Freeport-Mcmoran Inc | -241.0K | -100.0% | $14.16M | Exited |
| KEX Kirby Corp | -89.0K | -100.0% | $11.83M | Exited |
| CRS Carpenter Technology Corp | -15.0K | -41.8% | $9.27M | 10.07% |
| DHI Horton D R Inc | -66.5K | -100.0% | $9.13M | Exited |
| BLDR Builders FirstSource, Inc. | -98.2K | -100.0% | $8.09M | Exited |
| ATI Ati Inc | -31.4K | -34.2% | $6.18M | 9.31% |
| AMBP Ardagh Metal Packaging S.A. | -1.30M | -69.4% | $6.18M | 2.13% |
| CSTM Constellium Se | -176.4K | -26.8% | $5.62M | 12.01% |
| CENX Century Aluminum Co | -80.7K | -13.8% | $3.71M | 18.1% |
| Holding | Shares | Trade Value | Weight |
|---|---|---|---|
| MIDD MIDDLEBY Corp | +67.5K | $11.62M | 9.08% |
| Holding | Shares Sold | Trade Value | Prior Weight |
|---|---|---|---|
| HBM Hudbay Minerals Inc. | -706.0K | $14.76M | 7.5% |
| FCX Freeport-Mcmoran Inc | -241.0K | $14.16M | 7.2% |
| KEX Kirby Corp | -89.0K | $11.83M | 6.01% |
| DHI Horton D R Inc | -66.5K | $9.13M | 4.64% |
| BLDR Builders FirstSource, Inc. | -98.2K | $8.09M | 4.11% |
| ULCC Frontier Group Holdings, Inc. | -953.4K | $3.37M | 1.71% |
| # | Activity | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| 1 | CENX Century Aluminum Co | Basic Materials | 503.3K | $23.16M | 18.1% | -80.7K | -13.8% | Reduced | 0.51% |
| 2 | SXT Sensient Technologies Corp | Basic Materials | 131.7K | $16.24M | 12.69% | -24.9K | -15.9% | Reduced | 0.31% |
| 3 | CSTM Constellium Se | Industrials | 482.1K | $15.37M | 12.01% | -176.4K | -26.8% | Reduced | 0.35% |
| 4 | SARO StandardAero, Inc. | Industrials | 464.6K | $13.90M | 10.86% | +57.2K | +14.0% | Added | 0.14% |
| 5 | CRS Carpenter Technology Corp | Basic Materials | 20.9K | $12.89M | 10.07% | -15.0K | -41.8% | Reduced | 0.04% |
| 6 | ATI Ati Inc | Basic Materials | 60.4K | $11.91M | 9.31% | -31.4K | -34.2% | Reduced | 0.04% |
| 7 | MIDD MIDDLEBY Corp | Industrials | 67.5K | $11.62M | 9.08% | +67.5K | – | New | 0.14% |
| 8 | AA Alcoa Corp | Basic Materials | 208.2K | $10.85M | 8.48% | -25.5K | -10.9% | Reduced | 0.08% |
| 9 | HMY Harmony Gold Mining Co Ltd | Basic Materials | 612.9K | $9.32M | 7.29% | -53.8K | -8.1% | Reduced | 0.1% |
| 10 | AMBP Ardagh Metal Packaging S.A. | Basic Materials | 574.2K | $2.72M | 2.13% | -1.30M | -69.4% | Reduced | 0.1% |
Tip. Select a row to see that position’s full history at Mountaineer Partners Management.
As of its Q2 2026 13F filing, Mountaineer Partners Management, LLC’s five largest positions were Century Aluminum Co (CENX) at 18.1%, Sensient Technologies Corp (SXT) at 12.7%, Constellium Se (CSTM) at 12.0%, StandardAero, Inc. (SARO) at 10.9%, Carpenter Technology Corp (CRS) at 10.1% of the reported portfolio.
Mountaineer Partners Management, LLC reported a 13F portfolio worth $127.97M across 10 positions for Q2 2026. That is down 34.9% from the previous quarter.
Its largest purchases by value were MIDDLEBY Corp ($11.62M), StandardAero, Inc. ($1.71M). It opened 1 new positions.
Its largest sales by value were Hudbay Minerals Inc. ($14.76M), Freeport-Mcmoran Inc ($14.16M), Kirby Corp ($11.83M). It exited 6 positions entirely.
From the Form 13F-HR reports Mountaineer Partners Management, LLC files with the SEC each quarter, within 45 days of quarter end. A 13F lists long positions in US-listed equities and options; it excludes short positions, cash, bonds and most non-US holdings.
13F data reflects long positions in US-listed equities and options as reported to the SEC up to 45 days after quarter end. It excludes short positions, cash, bonds and most non-US securities, so it is not a complete picture of a manager’s assets.