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Mountaineer Partners Management, LLC

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13F filer, CIK 1730532, New York, NY

Mountaineer Partners Management, LLC reported $151,297,849 across 16 holdings for the quarter ended 2025-06-30, in a 13F-HR filed 2025-08-14. Its ten largest share positions make up 74.55% of the portfolio.

Filed (acceptance time not in the bulk data set), ingested 13F-HR 0000919574-25-004802

Period
2025-06-30
Reported value
$151M
Holdings
16
Top 10 weight
74.55%
New
3
Sold out
1

Largest buys vs the previous quarter

SecurityShares changeApprox. value
CRSnew+39,982$11.1M
SAROnew+290,730$9.2M
KEXnew+65,431$7.42M
CSTMadded+303,614$4.04M
ENTGadded+27,701$2.23M

Ranked by the share change valued at this quarter's implied price (value over shares in the 13F). A position sold out is valued at the previous quarter's price, its last report.

Largest sells vs the previous quarter

SecurityShares changeApprox. value
DHIexited-53,655-$6.82M
ATIreduced-58,405-$5.04M
ECGreduced-20,639-$1.31M
HBMreduced-36,623-$389K

Ranked by the share change valued at this quarter's implied price (value over shares in the 13F). A position sold out is valued at the previous quarter's price, its last report.

Holdings, Q2 2025

Share positions as resolved from 13F-HR 0000919574-25-004802, largest first. % of portfolio is the value over $151,297,849, the sum of the share positions whose value is usable for ratios (method).

SecurityHistorySharesValue% of portfolioChangeLatest eventTimeline
ECGEVERUS CONSTR GROUPQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2023Q3: restricted; 2023Q4: restricted; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: not reported; 2024Q4: 162,722 shares; 2025Q1: 226,857 shares; 2025Q2: 206,218 shares 206,218$13.1M8.66%-20,639Timeline
CENXCENTURY ALUM COQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2023Q3: restricted; 2023Q4: restricted; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: 1,407,831 shares; 2024Q4: 647,845 shares; 2025Q1: 639,373 shares; 2025Q2: 705,150 shares 705,150$12.7M8.4%+65,777Timeline
HBMHUDBAY MINERALS INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2023Q3: restricted; 2023Q4: restricted; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: 1,123,352 shares; 2024Q4: 1,104,563 shares; 2025Q1: 1,161,055 shares; 2025Q2: 1,124,432 shares 1,124,432$11.9M7.89%-36,623Timeline
VSHVISHAY INTERTECHNOLOGY INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2023Q3: restricted; 2023Q4: restricted; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: 1,102,278 shares; 2024Q4: 516,570 shares; 2025Q1: 659,478 shares; 2025Q2: 742,505 shares 742,505$11.8M7.79%+83,027Timeline
CSTMCONSTELLIUM SEQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2023Q3: restricted; 2023Q4: restricted; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: 549,134 shares; 2024Q4: 887,239 shares; 2025Q1: 542,068 shares; 2025Q2: 845,682 shares 845,682$11.2M7.43%+303,614Timeline
CRSCARPENTER TECHNOLOGY CORPQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2023Q3: restricted; 2023Q4: restricted; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: not reported; 2025Q2: 39,982 shares 39,982$11.1M7.3%newTimeline
FCXFREEPORT MCMORAN INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2023Q3: restricted; 2023Q4: restricted; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: 239,045 shares; 2024Q4: 246,840 shares; 2025Q1: 250,558 shares; 2025Q2: 252,961 shares 252,961$11M7.25%+2,403Timeline
ATIATI INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2023Q3: restricted; 2023Q4: restricted; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: 140,650 shares; 2024Q4: 182,670 shares; 2025Q1: 181,375 shares; 2025Q2: 122,970 shares 122,970$10.6M7.02%-58,405Timeline
ENTGENTEGRIS INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2023Q3: restricted; 2023Q4: restricted; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: 98,148 shares; 2024Q4: 99,860 shares; 2025Q1: 98,529 shares; 2025Q2: 126,230 shares 126,230$10.2M6.73%+27,701Timeline
SAROSTANDARDAERO INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2023Q3: restricted; 2023Q4: restricted; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: not reported; 2025Q2: 290,730 shares 290,730$9.2M6.08%newTimeline
AAALCOA CORPQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2023Q3: restricted; 2023Q4: restricted; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: 279,831 shares; 2024Q4: 257,778 shares; 2025Q1: 265,965 shares; 2025Q2: 304,781 shares 304,781$8.99M5.94%+38,816Timeline
KEXKIRBY CORPQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2023Q3: restricted; 2023Q4: restricted; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: not reported; 2025Q2: 65,431 shares 65,431$7.42M4.9%newTimeline
BLDRBUILDERS FIRSTSOURCE INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2023Q3: restricted; 2023Q4: restricted; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: 55,875 shares; 2024Q4: 55,875 shares; 2025Q1: 58,211 shares; 2025Q2: 62,464 shares 62,464$7.29M4.82%+4,253Timeline
AMBPARDAGH METAL PACKAGING S AQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2023Q3: restricted; 2023Q4: restricted; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: not reported; 2024Q4: 1,057,720 shares; 2025Q1: 1,057,720 shares; 2025Q2: 1,538,484 shares 1,538,484$6.58M4.35%+480,764Timeline
SJTSAN JUAN BASIN RTY TRQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2023Q3: restricted; 2023Q4: restricted; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: 719,054 shares; 2024Q4: 719,054 shares; 2025Q1: 719,054 shares; 2025Q2: 719,054 shares 719,054$4.3M2.84%0Timeline
NXENEXGEN ENERGY LTDQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2023Q3: restricted; 2023Q4: restricted; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: 564,507 shares; 2024Q4: 564,507 shares; 2025Q1: 564,507 shares; 2025Q2: 564,507 shares 564,507$3.92M2.59%0Timeline

Sold out in Q2 2025

Positions in the previous quarter's report that this quarter's report no longer lists.

SecurityShares beforeValue beforeType
DHID R HORTON INC53,655$6.82Mshares

How Q2 2025 was built

Available 13F filings of this filer for the quarter and their roles: the base report is the latest original or restatement, NEW HOLDINGS amendments filed after it are added (method).

FilingRoleAmendmentFiledAcceptedIngested
13F-HR 0000919574-25-004802 base2025-08-14acceptance time not in the bulk data set