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Disclosery

Corundum Group, Inc.: BRK-B position timeline

Available 13F reports, 13D and 13G stakes and each Form 3, 4 and 5 line of Corundum Group, Inc. on BRK-B, newest first. How the timeline and the estimate are built.

Corundum Group, Inc. held 2,589 BRK-B shares at 2026-06-30 per its 13F-HR filed 2026-08-07.

the latest 13F is the newest step

  1. period ended2026-06-30
    13F 2,589 shares
    Change vs previous 13F +37 shares

    0.38% of the 13F portfolio, value $1,295,510.

    13F-HR 0001486083-26-000003 filed by Corundum Group, Inc.
    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 2,552 shares
    Change vs previous 13F +37 shares

    0.41% of the 13F portfolio, value $1,222,918.

    13F-HR 0001486083-26-000002 filed by Corundum Group, Inc.
    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 2,515 shares
    Change vs previous 13F -94 shares

    0.42% of the 13F portfolio, value $1,264,165.

    13F-HR 0001486083-26-000001 filed by Corundum Group, Inc.
    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 2,609 shares
    Change vs previous 13F +5 shares

    0.54% of the 13F portfolio, value $1,311,649.

    13F-HR 0001486083-25-000006 filed by Corundum Group, Inc.
    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 2,604 shares
    Change vs previous 13F +516 shares

    0.56% of the 13F portfolio, value $1,264,945.

    13F-HR 0001486083-25-000005 filed by Corundum Group, Inc.
    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 2,088 shares
    Change vs previous 13F -1,559 shares

    0.53% of the 13F portfolio, value $1,112,027.

    13F-HR 0001486083-25-000004 filed by Corundum Group, Inc.
    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 3,647 shares
    Change vs previous 13F +2,088 shares

    0.62% of the 13F portfolio, value $1,653,112.

    13F-HR 0001486083-25-000001 filed by Corundum Group, Inc.
    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 1,559 shares
    Change vs previous 13F not available

    0.33% of the 13F portfolio, value $717,545.

    13F-HR 0001486083-24-000004 filed by Corundum Group, Inc.
    Filed (acceptance time not in the bulk data set), ingested

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