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FRONTIER CAPITAL MANAGEMENT CO LLC: AMTM position timeline

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

FRONTIER CAPITAL MANAGEMENT CO LLC held 4,143,971 AMTM 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 4,143,971 shares
    Change vs previous 13F -786,239 shares

    0.8% of the 13F portfolio, value $85,655,891.

    13F-HR 0001172661-26-003509 filed by FRONTIER CAPITAL MANAGEMENT CO 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 4,930,210 shares
    Change vs previous 13F -842,766 shares

    1.32% of the 13F portfolio, value $128,579,888.

    13F-HR 0001172661-26-002082 filed by FRONTIER CAPITAL MANAGEMENT CO 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 5,772,976 shares
    Change vs previous 13F +570,296 shares

    1.78% of the 13F portfolio, value $167,416,293.

    13F-HR 0001172661-26-000845 filed by FRONTIER CAPITAL MANAGEMENT CO 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 5,202,680 shares
    Change vs previous 13F -258,063 shares

    1.12% of the 13F portfolio, value $124,604,180.

    13F-HR 0001172661-25-004908 filed by FRONTIER CAPITAL MANAGEMENT CO 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 5,460,743 shares
    Change vs previous 13F +1,882,011 shares

    1.19% of the 13F portfolio, value $128,928,144.

    13F-HR 0001172661-25-003311 filed by FRONTIER CAPITAL MANAGEMENT CO 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 3,578,732 shares
    Change vs previous 13F not available

    0.71% of the 13F portfolio, value $65,132,931.

    13F-HR 0001172661-25-002022 filed by FRONTIER CAPITAL MANAGEMENT CO LLC
    Filed (acceptance time not in the bulk data set), ingested

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