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Mountaineer Partners Management, LLC: CSTM position timeline

Available 13F reports, 13D and 13G stakes and each Form 3, 4 and 5 line of Mountaineer Partners Management, LLC on CSTM, newest first. How the timeline and the estimate are built.

Mountaineer Partners Management, LLC held 482,130 CSTM shares at 2026-06-30 per its 13F-HR filed 2026-08-13.

the latest 13F is the newest step

  1. period ended2026-06-30
    13F/A 482,130 shares
    Change vs previous 13F -176,360 shares

    11.18% of the 13F portfolio, value $15,365,483.

    13F-HR 0000919574-26-005107 filed by Mountaineer Partners Management, LLC
    Filed (acceptance time not in the bulk data set), ingested

    Acceptance time not in the bulk data set (spec §4.2).

  2. period ended2026-03-31
    13F 658,490 shares
    Change vs previous 13F -22,974 shares

    8.04% of the 13F portfolio, value $16,185,685.

    13F-HR 0000919574-26-003280 filed by Mountaineer Partners Management, LLC
    Filed (acceptance time not in the bulk data set), ingested

    Acceptance time not in the bulk data set (spec §4.2).

  3. period ended2025-12-31
    13F 681,464 shares
    Change vs previous 13F -152,312 shares

    7.19% of the 13F portfolio, value $12,845,596.

    13F-HR 0000919574-26-000943 filed by Mountaineer Partners Management, LLC
    Filed (acceptance time not in the bulk data set), ingested

    Acceptance time not in the bulk data set (spec §4.2).

  4. period ended2025-09-30
    13F 833,776 shares
    Change vs previous 13F -11,906 shares

    7.22% of the 13F portfolio, value $12,406,587.

    13F-HR 0000919574-25-006893 filed by Mountaineer Partners Management, LLC
    Filed (acceptance time not in the bulk data set), ingested

    Acceptance time not in the bulk data set (spec §4.2).

  5. period ended2025-06-30
    13F 845,682 shares
    Change vs previous 13F +303,614 shares

    7.43% of the 13F portfolio, value $11,247,570.

    13F-HR 0000919574-25-004802 filed by Mountaineer Partners Management, LLC
    Filed (acceptance time not in the bulk data set), ingested

    Acceptance time not in the bulk data set (spec §4.2).

  6. period ended2025-03-31
    13F 542,068 shares
    Change vs previous 13F -345,171 shares

    5.23% of the 13F portfolio, value $5,469,466.

    13F-HR 0000919574-25-003166 filed by Mountaineer Partners Management, LLC
    Filed (acceptance time not in the bulk data set), ingested

    Acceptance time not in the bulk data set (spec §4.2).

  7. period ended2024-12-31
    13F 887,239 shares
    Change vs previous 13F +338,105 shares

    6.67% of the 13F portfolio, value $9,111,944.

    13F-HR 0000919574-25-001213 filed by Mountaineer Partners Management, LLC
    Filed (acceptance time not in the bulk data set), ingested

    Acceptance time not in the bulk data set (spec §4.2).

  8. period ended2024-09-30
    13F/A 549,134 shares
    Change vs previous 13F not available

    5.57% of the 13F portfolio, value $8,928,919.

    13F-HR/A 0000919574-24-006813 filed by Mountaineer Partners Management, LLC
    Filed (acceptance time not in the bulk data set), ingested

    Acceptance time not in the bulk data set (spec §4.2).