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Mountaineer Partners Management, LLC

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13F filer, CIK 1730532, New York, NY

Mountaineer Partners Management, LLC reported $178,724,898 across 17 holdings for the quarter ended 2025-12-31, in a 13F-HR filed 2026-02-13. Its ten largest share positions make up 76.24% of the portfolio.

Filed (acceptance time not in the bulk data set), ingested 13F-HR 0000919574-26-000943

Period
2025-12-31
Reported value
$179M
Holdings
17
Top 10 weight
76.24%
New
3
Sold out
4

Largest buys vs the previous quarter

SecurityShares changeApprox. value
SXTnew+117,090$11M
DHIadded+37,128$5.35M
ULCCnew+953,375$4.49M
CCJnew+42,424$3.88M
BLDRadded+33,332$3.43M

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
ECGexited-169,844-$14.6M
ENTGexited-123,234-$11.4M
VSHexited-742,177-$11.4M
UECexited-320,952-$4.28M
HBMreduced-168,172-$3.34M

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, Q4 2025

Share positions as resolved from 13F-HR 0000919574-26-000943, largest first. % of portfolio is the value over $178,724,898, the sum of the share positions whose value is usable for ratios (method).

SecurityHistorySharesValue% of portfolioChangeLatest eventTimeline
CENXCENTURY ALUM COQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: 1,407,831 shares; 2024Q4: 647,845 shares; 2025Q1: 639,373 shares; 2025Q2: 705,150 shares; 2025Q3: 661,043 shares; 2025Q4: 608,475 shares 608,475$23.8M13.34%-52,568Timeline
HBMHUDBAY MINERALS INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: 1,123,352 shares; 2024Q4: 1,104,563 shares; 2025Q1: 1,161,055 shares; 2025Q2: 1,124,432 shares; 2025Q3: 955,419 shares; 2025Q4: 787,247 shares 787,247$15.6M8.74%-168,172Timeline
ATIATI INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: 140,650 shares; 2024Q4: 182,670 shares; 2025Q1: 181,375 shares; 2025Q2: 122,970 shares; 2025Q3: 144,020 shares; 2025Q4: 128,909 shares 128,909$14.8M8.28%-15,111Timeline
FCXFREEPORT MCMORAN INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: 239,045 shares; 2024Q4: 246,840 shares; 2025Q1: 250,558 shares; 2025Q2: 252,961 shares; 2025Q3: 294,049 shares; 2025Q4: 266,327 shares 266,327$13.5M7.57%-27,722Timeline
AAALCOA CORPQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: 279,831 shares; 2024Q4: 257,778 shares; 2025Q1: 265,965 shares; 2025Q2: 304,781 shares; 2025Q3: 296,642 shares; 2025Q4: 241,994 shares 241,994$12.9M7.2%-54,648Timeline
CSTMCONSTELLIUM SEQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: 549,134 shares; 2024Q4: 887,239 shares; 2025Q1: 542,068 shares; 2025Q2: 845,682 shares; 2025Q3: 833,776 shares; 2025Q4: 681,464 shares 681,464$12.8M7.19%-152,312Timeline
CRSCARPENTER TECHNOLOGY CORPQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: not reported; 2025Q2: 39,982 shares; 2025Q3: 40,849 shares; 2025Q4: 36,690 shares 36,690$11.6M6.46%-4,159Timeline
SXTSENSIENT TECHNOLOGIES CORPQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: not reported; 2025Q2: not reported; 2025Q3: not reported; 2025Q4: 117,090 shares 117,090$11M6.16%newTimeline
SAROSTANDARDAERO INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: not reported; 2025Q2: 290,730 shares; 2025Q3: 290,730 shares; 2025Q4: 367,498 shares 367,498$10.5M5.9%+76,768Timeline
BLDRBUILDERS FIRSTSOURCE INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: 55,875 shares; 2024Q4: 55,875 shares; 2025Q1: 58,211 shares; 2025Q2: 62,464 shares; 2025Q3: 60,759 shares; 2025Q4: 94,091 shares 94,091$9.68M5.42%+33,332Timeline
KEXKIRBY CORPQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: not reported; 2025Q2: 65,431 shares; 2025Q3: 65,431 shares; 2025Q4: 87,444 shares 87,444$9.63M5.39%+22,013Timeline
DHID R HORTON INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: 50,921 shares; 2024Q4: 51,015 shares; 2025Q1: 53,655 shares; 2025Q2: not reported; 2025Q3: 27,876 shares; 2025Q4: 65,004 shares 65,004$9.36M5.24%+37,128Timeline
AMBPARDAGH METAL PACKAGING S AQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: not reported; 2024Q4: 1,057,720 shares; 2025Q1: 1,057,720 shares; 2025Q2: 1,538,484 shares; 2025Q3: 1,538,484 shares; 2025Q4: 1,469,480 shares 1,469,480$6.02M3.37%-69,004Timeline
NXENEXGEN ENERGY LTDQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: 564,507 shares; 2024Q4: 564,507 shares; 2025Q1: 564,507 shares; 2025Q2: 564,507 shares; 2025Q3: 564,507 shares; 2025Q4: 538,042 shares 538,042$4.95M2.77%-26,465Timeline
ULCCFRONTIER GROUP HLDGS INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: not reported; 2025Q2: not reported; 2025Q3: not reported; 2025Q4: 953,375 shares 953,375$4.49M2.51%newTimeline
SJTSAN JUAN BASIN RTY TRQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: 719,054 shares; 2024Q4: 719,054 shares; 2025Q1: 719,054 shares; 2025Q2: 719,054 shares; 2025Q3: 719,054 shares; 2025Q4: 732,351 shares 732,351$4.12M2.3%+13,297Timeline
CCJCAMECO CORPQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q1: restricted; 2024Q2: restricted; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: not reported; 2025Q2: not reported; 2025Q3: not reported; 2025Q4: 42,424 shares 42,424$3.88M2.17%newTimeline

Sold out in Q4 2025

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

SecurityShares beforeValue beforeType
ECGEVERUS CONSTR GROUP169,844$14.6Mshares
ENTGENTEGRIS INC123,234$11.4Mshares
VSHVISHAY INTERTECHNOLOGY INC742,177$11.4Mshares
UECURANIUM ENERGY CORP320,952$4.28Mshares

How Q4 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 0000919574-26-000943 base2026-02-13acceptance time not in the bulk data set