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MASON CAPITAL MANAGEMENT LLC: ATS position timeline

Available 13F reports, 13D and 13G stakes and each Form 3, 4 and 5 line of MASON CAPITAL MANAGEMENT LLC on ATS, newest first. How the timeline and the estimate are built.

MASON CAPITAL MANAGEMENT LLC held 16,404,170 ATS shares at 2026-06-30 per its 13F-HR filed 2026-08-14.

the latest 13F is the newest step

  1. period ended2026-06-30
    13F 16,404,170 shares
    Change vs previous 13F 0 shares

    77.8% of the 13F portfolio, value $472,112,013.

    13F-HR 0001104659-26-097052 filed by MASON CAPITAL 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 16,404,170 shares
    Change vs previous 13F +840,602 shares

    75.51% of the 13F portfolio, value $462,597,594.

    13F-HR 0001104659-26-062410 filed by MASON CAPITAL 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 15,563,568 shares
    Change vs previous 13F 0 shares

    76.32% of the 13F portfolio, value $428,620,663.

    13F-HR 0001104659-26-016335 filed by MASON CAPITAL 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 15,563,568 shares
    Change vs previous 13F 0 shares

    82.99% of the 13F portfolio, value $407,765,482.

    13F-HR 0001104659-25-111862 filed by MASON CAPITAL 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 15,563,568 shares
    Change vs previous 13F 0 shares

    97% of the 13F portfolio, value $496,166,548.

    13F-HR 0001104659-25-078546 filed by MASON CAPITAL 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 15,563,568 shares
    Change vs previous 13F +648,803 shares

    90.83% of the 13F portfolio, value $387,999,750.

    13F-HR 0001104659-25-049417 filed by MASON CAPITAL 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 14,914,765 shares
    Change vs previous 13F 0 shares

    96.62% of the 13F portfolio, value $454,602,037.

    13F-HR 0001104659-25-014023 filed by MASON CAPITAL 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 14,914,765 shares
    Change vs previous 13F not available

    86.21% of the 13F portfolio, value $433,273,923.

    13F-HR 0001104659-24-118983 filed by MASON CAPITAL MANAGEMENT LLC
    Filed (acceptance time not in the bulk data set), ingested

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