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Disclosery

Mountaineer Partners Management, LLC: ATI position timeline

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

Mountaineer Partners Management, LLC held 60,419 ATI 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 60,419 shares
    Change vs previous 13F -31,365 shares

    8.66% of the 13F portfolio, value $11,908,585.

    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 91,784 shares
    Change vs previous 13F -37,125 shares

    6.63% of the 13F portfolio, value $13,350,901.

    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 128,909 shares
    Change vs previous 13F -15,111 shares

    8.28% of the 13F portfolio, value $14,793,597.

    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 144,020 shares
    Change vs previous 13F +21,050 shares

    6.81% of the 13F portfolio, value $11,714,587.

    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 122,970 shares
    Change vs previous 13F -58,405 shares

    7.02% of the 13F portfolio, value $10,617,230.

    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 181,375 shares
    Change vs previous 13F -1,295 shares

    9.03% of the 13F portfolio, value $9,436,941.

    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 182,670 shares
    Change vs previous 13F +42,020 shares

    7.36% of the 13F portfolio, value $10,054,157.

    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 140,650 shares
    Change vs previous 13F not available

    5.87% of the 13F portfolio, value $9,410,891.

    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).