Mountaineer Partners Management, LLC
Mountaineer Partners Management, LLC reported 11 US-listed holdings worth $137.5 million in its 13F for the quarter ended 30 June 2026, filed 14 August 2026. Its largest: Century Aluminum Co. (16.8%), Sensient Technologies Corp. (11.8%) and Constellium SE (11.2%). Against the quarter before, it opened 1 position, added to 1, trimmed 9 and sold out of 6.
The 11 largest of its 11 positions, each sized by its share of the reported holdings, coloured by the change in shares against Q1 2026.
What the fund reported holding at each quarter's end; hover a bar for the number of positions
What its reported holdings returned
Held through each quarter, the holdings it reported returned +60.8% over the 7 quarters to 30 June 2026, against +30.2% for the S&P 500.
Not the fund's own return: each 13F's holdings are kept unchanged until the next one, so trades inside a quarter, dividends, cash and fees are left out. A rough guide to how its picks have done over time.
What it did on the quarter
Its positions against its 13F for the quarter to 31 March 2026; a change under 0.1% of a position counts as held
Opened 1
- Middleby Corp. MIDD$11.6 million
Added to 1
- StandardAero, Inc. SARO+57,160 shares · +14%
Trimmed 9
- Carpenter Technology Corp. CRS-15,035 shares · -42%
- ATI Inc. ATI-31,365 shares · -34%
- Constellium SE CSTM-176,360 shares · -27%
- Century Aluminum Co. CENX-80,688 shares · -14%
- Sensient Technologies Corp. SXT-24,857 shares · -16%
- Alcoa Corp. AA-25,522 shares · -11%
- Harmony Gold Mining Co. Ltd HMY-53,786 shares · -8%
- Ardagh Metal Packaging S A AMBP-155,848 shares · -8%
and 1 more in the table below
Sold out of 6
- Hudbay Minerals Inc. HBM$14.8 million last quarter
- Freeport-McMoRan Inc. FCX$14.2 million last quarter
- Kirby Corp. KEX$11.8 million last quarter
- D.R. Horton, Inc. DHI$9.1 million last quarter
- Builders Firstsource Inc. BLDR$8.1 million last quarter
- Frontier Group Holdings Inc. ULCC$3.4 million last quarter
What it holds
| Company | Shares | Value | Of its book | Change in shares |
|---|---|---|---|---|
| Century Aluminum Co. CENX | 503.3K | $23.2 million | 16.84% | -80.7K |
| Sensient Technologies Corp. SXT | 131.7K | $16.2 million | 11.81% | -24.9K |
| Constellium SE CSTM | 482.1K | $15.4 million | 11.18% | -176.4K |
| StandardAero, Inc. SARO | 464.6K | $13.9 million | 10.11% | +57.2K |
| Carpenter Technology Corp. CRS | 20.9K | $12.9 million | 9.37% | -15.0K |
| ATI Inc. ATI | 60.4K | $11.9 million | 8.66% | -31.4K |
| Middleby Corp. MIDD | 67.5K | $11.6 million | 8.45% | new |
| Alcoa Corp. AA | 208.2K | $10.9 million | 7.89% | -25.5K |
| Harmony Gold Mining Co. Ltd HMY | 612.9K | $9.3 million | 6.78% | -53.8K |
| Ardagh Metal Packaging S A AMBP | 1.7M | $8.2 million | 5.94% | -155.8K |
| Cameco Corp. CCJ | 39.9K | $4.1 million | 2.96% | -2.5K |