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Mountaineer Partners Management, LLC

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13F filer, CIK 1730532, New York, NY

Mountaineer Partners Management, LLC reported $137,477,683 across 11 holdings for the quarter ended 2026-06-30, in a 13F-HR filed 2026-08-13. Its ten largest share positions make up 97.04% of the portfolio.

Filed (acceptance time not in the bulk data set), ingested 13F-HR 0000919574-26-005107

Period
2026-06-30
Reported value
$137M
Holdings
11
Top 10 weight
97.04%
New
1
Sold out
6

Largest buys vs the previous quarter

SecurityShares changeApprox. value
MIDDnew+67,536$11.6M
SAROadded+57,160$1.71M

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
HBMexited-706,040-$14.8M
FCXexited-240,973-$14.2M
KEXexited-89,017-$11.8M
CRSreduced-15,035-$9.27M
DHIexited-66,541-$9.13M

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 2026

Share positions as resolved from 13F-HR 0000919574-26-005107, largest first. % of portfolio is the value over $137,477,683, 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; 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; 2026Q1: 583,997 shares; 2026Q2: 503,309 shares 503,309$23.2M16.84%-80,688Timeline
SXTSENSIENT TECHNOLOGIES CORPQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: not reported; 2025Q2: not reported; 2025Q3: not reported; 2025Q4: 117,090 shares; 2026Q1: 156,584 shares; 2026Q2: 131,727 shares 131,727$16.2M11.81%-24,857Timeline
CSTMCONSTELLIUM SEQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q3: 549,134 shares; 2024Q4: 887,239 shares; 2025Q1: 542,068 shares; 2025Q2: 845,682 shares; 2025Q3: 833,776 shares; 2025Q4: 681,464 shares; 2026Q1: 658,490 shares; 2026Q2: 482,130 shares 482,130$15.4M11.18%-176,360Timeline
SAROSTANDARDAERO INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: not reported; 2025Q2: 290,730 shares; 2025Q3: 290,730 shares; 2025Q4: 367,498 shares; 2026Q1: 407,435 shares; 2026Q2: 464,595 shares 464,595$13.9M10.11%+57,160Timeline
CRSCARPENTER TECHNOLOGY CORPQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: not reported; 2025Q2: 39,982 shares; 2025Q3: 40,849 shares; 2025Q4: 36,690 shares; 2026Q1: 35,929 shares; 2026Q2: 20,894 shares 20,894$12.9M9.37%-15,035Timeline
ATIATI INCQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q3: 140,650 shares; 2024Q4: 182,670 shares; 2025Q1: 181,375 shares; 2025Q2: 122,970 shares; 2025Q3: 144,020 shares; 2025Q4: 128,909 shares; 2026Q1: 91,784 shares; 2026Q2: 60,419 shares 60,419$11.9M8.66%-31,365Timeline
MIDDMIDDLEBY CORPQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: not reported; 2025Q2: not reported; 2025Q3: not reported; 2025Q4: not reported; 2026Q1: not reported; 2026Q2: 67,536 shares 67,536$11.6M8.45%newTimeline
AAALCOA CORPQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q3: 279,831 shares; 2024Q4: 257,778 shares; 2025Q1: 265,965 shares; 2025Q2: 304,781 shares; 2025Q3: 296,642 shares; 2025Q4: 241,994 shares; 2026Q1: 233,687 shares; 2026Q2: 208,165 shares 208,165$10.9M7.89%-25,522Timeline
HMYHARMONY GOLD MNG LTDQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: not reported; 2025Q2: not reported; 2025Q3: not reported; 2025Q4: not reported; 2026Q1: 666,735 shares; 2026Q2: 612,949 shares 612,949$9.32M6.78%-53,786Timeline
AMBPARDAGH METAL PACKAGING S AQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 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; 2026Q1: 1,878,082 shares; 2026Q2: 1,722,234 shares 1,722,234$8.16M5.94%-155,848Timeline
CCJCAMECO CORPQuarterly shares; oldest to newest; scale is this security's eight-quarter maximum; 2024Q3: not reported; 2024Q4: not reported; 2025Q1: not reported; 2025Q2: not reported; 2025Q3: not reported; 2025Q4: 42,424 shares; 2026Q1: 42,424 shares; 2026Q2: 39,903 shares 39,903$4.06M2.96%-2,521Timeline

Sold out in Q2 2026

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

SecurityShares beforeValue beforeType
HBMHUDBAY MINERALS INC706,040$14.8Mshares
FCXFREEPORT MCMORAN INC240,973$14.2Mshares
KEXKIRBY CORP89,017$11.8Mshares
DHID R HORTON INC66,541$9.13Mshares
BLDRBUILDERS FIRSTSOURCE INC98,203$8.09Mshares
ULCCFRONTIER GROUP HLDGS INC953,375$3.37Mshares

How Q2 2026 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 0000919574-26-005107 base2026-08-13acceptance time not in the bulk data set
13F-HR/A 0000919574-26-005443 addednew holdings2026-08-14acceptance time not in the bulk data set

Filings

Every filing of this filer: 13F reports and notices, the 13D and 13G it filed or is a reporting person of, and Forms 3, 4 and 5 it reported as an owner.

FilingSubjectFiledAcceptedIngested
13F-HR/A 0000919574-26-005443 Quarter ended 2026-06-302026-08-14acceptance time not in the bulk data set
13F-HR 0000919574-26-005107 Quarter ended 2026-06-302026-08-13acceptance time not in the bulk data set
13F-HR 0000919574-26-003280 Quarter ended 2026-03-312026-05-15acceptance time not in the bulk data set
13F-HR 0000919574-26-000943 Quarter ended 2025-12-312026-02-13acceptance time not in the bulk data set
13F-HR 0000919574-25-006893 Quarter ended 2025-09-302025-11-14acceptance time not in the bulk data set
13F-HR 0000919574-25-004802 Quarter ended 2025-06-302025-08-14acceptance time not in the bulk data set
13F-HR 0000919574-25-003166 Quarter ended 2025-03-312025-05-15acceptance time not in the bulk data set
13F-HR 0000919574-25-001213 Quarter ended 2024-12-312025-02-14acceptance time not in the bulk data set
13F-HR/A 0000919574-24-006813 Quarter ended 2024-09-302024-11-15acceptance time not in the bulk data set
13F-HR 0000919574-24-006445 Quarter ended 2024-09-302024-11-14acceptance time not in the bulk data set
13F-HR 0000919574-24-004619 Quarter ended 2024-06-302024-08-14acceptance time not in the bulk data set
13F-HR 0000919574-24-003088 Quarter ended 2024-03-312024-05-15acceptance time not in the bulk data set
13F-HR 0000919574-24-001267 Quarter ended 2023-12-312024-02-14acceptance time not in the bulk data set
13F-HR 0000919574-23-006317 Quarter ended 2023-09-302023-11-14acceptance time not in the bulk data set
13F-HR 0000919574-23-004636 Quarter ended 2023-06-302023-08-14acceptance time not in the bulk data set
13F-HR 0000919574-23-003182 Quarter ended 2023-03-312023-05-15acceptance time not in the bulk data set
13F-HR 0000919574-23-001219 Quarter ended 2022-12-312023-02-14acceptance time not in the bulk data set
13F-HR 0000919574-22-006551 Quarter ended 2022-09-302022-11-14acceptance time not in the bulk data set
13F-HR 0000919574-22-004911 Quarter ended 2022-06-302022-08-15acceptance time not in the bulk data set
13F-HR 0000919574-22-003299 Quarter ended 2022-03-312022-05-16acceptance time not in the bulk data set
13F-HR 0000919574-22-001053 Quarter ended 2021-12-312022-02-14acceptance time not in the bulk data set
13F-HR 0000919574-21-006888 Quarter ended 2021-09-302021-11-15acceptance time not in the bulk data set
13F-HR 0000919574-21-005233 Quarter ended 2021-06-302021-08-16acceptance time not in the bulk data set
13F-HR 0000919574-21-003454 Quarter ended 2021-03-312021-05-14acceptance time not in the bulk data set
13F-HR 0000919574-21-000966 Quarter ended 2020-12-312021-02-12acceptance time not in the bulk data set
13F-HR 0000919574-20-006887 Quarter ended 2020-09-302020-11-13acceptance time not in the bulk data set
13F-HR 0000919574-20-005042 Quarter ended 2020-06-302020-08-13acceptance time not in the bulk data set
13F-HR 0000919574-20-003334 Quarter ended 2020-03-312020-05-14acceptance time not in the bulk data set
13F-HR 0000919574-20-001026 Quarter ended 2019-12-312020-02-13acceptance time not in the bulk data set
13F-HR 0000919574-19-006898 Quarter ended 2019-09-302019-11-13acceptance time not in the bulk data set
13F-HR 0000919574-19-005031 Quarter ended 2019-06-302019-08-13acceptance time not in the bulk data set
13F-HR 0000919574-19-003347 Quarter ended 2019-03-312019-05-14acceptance time not in the bulk data set
13F-HR 0000919574-19-001512 Quarter ended 2018-12-312019-02-14acceptance time not in the bulk data set