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WELLINGTON MANAGEMENT GROUP LLP: AMSC position timeline

Available 13F reports, 13D and 13G stakes and each Form 3, 4 and 5 line of WELLINGTON MANAGEMENT GROUP LLP on AMSC, newest first. How the timeline and the estimate are built.

WELLINGTON MANAGEMENT GROUP LLP held 85,244 AMSC 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 85,244 shares
    Change vs previous 13F +85,244 shares

    <0.01% of the 13F portfolio, value $3,538,478.

    13F-HR 0000902219-26-000311 filed by WELLINGTON MANAGEMENT GROUP LLP
    Filed (acceptance time not in the bulk data set), ingested

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

  2. period ended2025-12-31
    13F 0 shares
    Change vs previous 13F -399,246 shares

    13F-HR 0000902219-26-000103 filed by WELLINGTON MANAGEMENT GROUP LLP
    Filed (acceptance time not in the bulk data set), ingested

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

    Exited: the 13F for this period no longer lists the position.

  3. period ended2025-09-30
    13F 399,246 shares
    Change vs previous 13F -32,343 shares

    <0.01% of the 13F portfolio, value $23,711,220.

    13F-HR 0000902219-25-000462 filed by WELLINGTON MANAGEMENT GROUP LLP
    Filed (acceptance time not in the bulk data set), ingested

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

  4. period ended2025-06-30
    13F 431,589 shares
    Change vs previous 13F +142,416 shares

    <0.01% of the 13F portfolio, value $15,835,001.

    13F-HR 0000902219-25-000356 filed by WELLINGTON MANAGEMENT GROUP LLP
    Filed (acceptance time not in the bulk data set), ingested

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

  5. period ended2025-03-31
    13F 289,173 shares
    Change vs previous 13F -172,057 shares

    <0.01% of the 13F portfolio, value $5,245,599.

    13F-HR 0000902219-25-000242 filed by WELLINGTON MANAGEMENT GROUP LLP
    Filed (acceptance time not in the bulk data set), ingested

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

  6. period ended2024-12-31
    13F/A 461,230 shares
    Change vs previous 13F not available

    <0.01% of the 13F portfolio, value $11,360,095.

    13F-HR 0000902219-25-000131 filed by WELLINGTON MANAGEMENT GROUP LLP
    Filed (acceptance time not in the bulk data set), ingested

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