CIK: 0001730532
Total reported value
$201.3M
Reporting period: 2026-03-31 · Number of holdings: 32
Mountaineer Partners Management, LLC disclosed 32 holdings in its latest 13F filing for the period ending 2026-03-31, with total reported value of $201.3M and a quarterly turnover rate of 27.0%.
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Mountaineer Partners Management, LLC's disclosed holdings carry a Herfindahl concentration index of 0.080 — mathematically equivalent to about 12 equally-sized positions, well below its 32 actual disclosed holdings. That gap points to a strategy built around a small core of high-conviction bets rather than broad diversification.
Position sizes are fairly uniform across the portfolio (a coefficient of variation of 0.55), suggesting a disciplined, rules-based approach to how much capital goes into each idea.
No strong tilt toward either adding to existing winners or initiating outsized new positions was observed in the latest reported quarter.
Sector classification currently covers about 69% of this portfolio's disclosed value; the remainder includes holdings (e.g. unmapped tickers, options, or other security types) not yet covered by our sector mapping.
Add CENX
-4.0% $10.4M
Trim ATI
-28.8% -$1.4M
Trim HBM
-10.3% -$870.6K
Trim BLDR
+4.4% -$1.6M
Add CSTM
-3.4% $3.3M
Trim ULCC
0.0% -$1.1M
Showing top 16 holdings (of 32 total)
| # | Ticker | Issuer | Asset Subclass | Weight | Weight Change | Shares Change | 4Q Trend |
|---|---|---|---|---|---|---|---|
| 1 | CENX | Century Aluminum Company | Stock-Materials | 17.02% | +3.68% | -4.02% | |
| 2 | CSTM | Constellium SE | Stock-Other | 8.04% | +0.85% | -3.37% | |
| 3 | AA | Alcoa CORP | Stock-Materials | 7.70% | +0.50% | -3.43% | |
| 4 | HBM | Hudbay Minerals INC | Stock-Other | 7.33% | -1.41% | -10.32% | |
| 5 | FCX | Freeport-mcmoran INC | Stock-Materials | 7.04% | -0.53% | -9.52% | |
| 6 | CRS | Carpenter Technology | Stock-Industrials | 7.03% | +0.57% | -2.07% | |
| 7 | SXT | Sensient Technologies CORP | Stock-Materials | 6.72% | +0.56% | +33.73% | |
| 8 | ATI | Ati INC | Stock-Industrials | 6.63% | -1.65% | -28.80% | |
| 9 | KEX | Kirby CORP | Stock-Industrials | 5.88% | +0.49% | +1.80% | |
| 10 | SARO | Standardaero INC | Stock-Other | 5.23% | -0.67% | +10.87% | |
| 11 | HMY | Harmony Gold Mng-spon Adr | Stock-Other | 5.09% | +5.09% | NEW | |
| 12 | DHI | Dr Horton INC | Stock-Consumer Disc | 4.54% | -0.70% | +2.36% | |
| 13 | BLDR | Builders Firstsource INC | Stock-Industrials | 4.02% | -1.40% | +4.37% | |
| 14 | AMBP | Ardagh Metal Packaging S.A. | Stock-Other | 3.78% | +0.41% | +27.81% | |
| 15 | CCJ | Cameco CORP | Stock-Energy | 2.29% | +0.12% | — | |
| 16 | ULCC | Frontier Group Holdings INC | Stock-Other | 1.67% | -0.84% | — |
Performance for Q3 2026
-5.2%
Performance Last 4 Quarters
+67.1%
| Period | Holdings | Total value | Stability | Top holdings |
|---|---|---|---|---|
| 2026-03-31 | 32 | $201.3M | 27 | |
| 2025-12-31 | 34 | $178.7M | 52 | |
| 2025-09-30 | 36 | $171.9M | 44 | |
| 2025-06-30 | 32 | $151.3M | 0 | |
| 2025-03-31 | 28 | $104.5M | 100 | |
| 2024-12-31 | 34 | $136.6M | 0 | |
| 2024-09-30 | 30 | $6.6B | 0 | |
| 2024-06-30 | 32 | $192.2M | 0 | |
| 2024-03-31 | 32 | $216.6M | 0 | |
| 2023-12-31 | 28 | $196.8M | 0 | |
| 2023-09-30 | 28 | $156.0M | 0 | |
| 2023-06-30 | 28 | $181.3M | 0 | |
| 2023-03-31 | 26 | $137.6M | 0 | |
| 2022-12-31 | 18 | $105.3M | 0 | |
| 2022-09-30 | 18 | $79.1M | 0 | |
| 2022-06-30 | 20 | $99.4M | 0 | |
| 2022-03-31 | 30 | $181.9M | 0 | |
| 2021-12-31 | 34 | $183.8M | 0 | |
| 2021-09-30 | 32 | $153.1M | 0 | |
| 2021-06-30 | 28 | $137.3M | 100 | |
| 2021-03-31 | 30 | $142.7M | 67 | |
| 2020-12-31 | 34 | $139.4M | 94 | |
| 2020-09-30 | 31 | $115.8M | 48 | |
| 2020-06-30 | 25 | $74.5M | 81 | |
| 2020-03-31 | 31 | $70.3M | 88 | |
| 2019-12-31 | 25 | $89.8M | 76 | |
| 2019-09-30 | 25 | $99.3M | 95 | |
| 2019-06-30 | 27 | $216.7M | 80 | |
| 2019-03-31 | 26 | $117.2M | 49 | |
| 2018-12-31 | 28 | $117.6M | 0 |
Mountaineer Partners Management, LLC's most significant position changes for 2026-03-31: New buy: Harmony Gold Mng-spon Adr (HMY); Sold out: Nexgen Energy LTD (NXE); Sold out: San Juan Basin Royalty Tr (SJT); Trim: Century Aluminum Company (CENX) — shares -4.02%; Trim: Ati INC (ATI) — shares -28.80%.
| # | Ticker | Issuer | Weight Change | Shares Change | Action |
|---|---|---|---|---|---|
| 1 | CENX | Century Aluminum Company | +3.7% | -4.02% | Trim |
| 2 | CSTM | Constellium SE | +0.9% | -3.37% | Trim |
| 3 | CRS | Carpenter Technology | +0.6% | -2.07% | Trim |
| 4 | SXT | Sensient Technologies CORP | +0.6% | +33.73% | Add |
| 5 | AA | Alcoa CORP | +0.5% | -3.43% | Trim |
| 6 | KEX | Kirby CORP | +0.5% | +1.80% | Add |
| 7 | AMBP | Ardagh Metal Packaging S.A. | +0.4% | +27.81% | Add |
| 8 | CCJ | Cameco CORP | +0.1% | — | Unchanged |
| 9 | FCX | Freeport-mcmoran INC | -0.5% | -9.52% | Trim |
| 10 | SARO | Standardaero INC | -0.7% | +10.87% | Add |
| 11 | DHI | Dr Horton INC | -0.7% | +2.36% | Add |
| 12 | ULCC | Frontier Group Holdings INC | -0.8% | — | Unchanged |
| 13 | BLDR | Builders Firstsource INC | -1.4% | +4.37% | Add |
| 14 | HBM | Hudbay Minerals INC | -1.4% | -10.32% | Trim |
| 15 | ATI | Ati INC | -1.7% | -28.80% | Trim |
| 16 | HMY | Harmony Gold Mng-spon Adr | — | NEW | New buy |
| 17 | NXE | Nexgen Energy LTD | — | EXIT | Sold out |
| 18 | SJT | San Juan Basin Royalty Tr | — | EXIT | Sold out |
| Period | Filed | Type | EDGAR |
|---|---|---|---|
| 2026-03-31 | 2026-05-15 | 13F-HR | View on EDGAR |
| 2025-12-31 | 2026-02-13 | 13F-HR | View on EDGAR |
| 2025-09-30 | 2025-11-14 | 13F-HR | View on EDGAR |
| 2025-06-30 | 2025-08-14 | 13F-HR | View on EDGAR |
| 2025-03-31 | 2025-05-15 | 13F-HR | View on EDGAR |
| 2024-12-31 | 2025-02-14 | 13F-HR | View on EDGAR |
| 2024-09-30 | 2024-11-15 | Amendment | View on EDGAR |
| 2024-09-30 | 2024-11-14 | 13F-HR | View on EDGAR |
| 2024-06-30 | 2024-08-14 | 13F-HR | View on EDGAR |
| 2024-03-31 | 2024-05-15 | 13F-HR | View on EDGAR |
| 2023-12-31 | 2024-02-14 | 13F-HR | View on EDGAR |
| 2023-09-30 | 2023-11-14 | 13F-HR | View on EDGAR |
| 2023-06-30 | 2023-08-14 | 13F-HR | View on EDGAR |
| 2023-03-31 | 2023-05-15 | 13F-HR | View on EDGAR |
| 2022-12-31 | 2023-02-14 | 13F-HR | View on EDGAR |
| 2022-09-30 | 2022-11-14 | 13F-HR | View on EDGAR |
| 2022-06-30 | 2022-08-15 | 13F-HR | View on EDGAR |
| 2022-03-31 | 2022-05-16 | 13F-HR | View on EDGAR |
| 2021-12-31 | 2022-02-14 | 13F-HR | View on EDGAR |
| 2021-09-30 | 2021-11-15 | 13F-HR | View on EDGAR |
| 2021-06-30 | 2021-08-16 | 13F-HR | View on EDGAR |
| 2021-03-31 | 2021-05-14 | 13F-HR | View on EDGAR |
| 2020-12-31 | 2021-02-12 | 13F-HR | View on EDGAR |
| 2020-09-30 | 2020-11-13 | 13F-HR | View on EDGAR |
| 2020-06-30 | 2020-08-13 | 13F-HR | View on EDGAR |
| 2020-03-31 | 2020-05-14 | 13F-HR | View on EDGAR |
| 2019-12-31 | 2020-02-13 | 13F-HR | View on EDGAR |
| 2019-09-30 | 2019-11-13 | 13F-HR | View on EDGAR |
| 2019-06-30 | 2019-08-13 | 13F-HR | View on EDGAR |
| 2019-03-31 | 2019-05-14 | 13F-HR | View on EDGAR |
| 2018-12-31 | 2019-02-14 | 13F-HR | View on EDGAR |
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