SCHEDULE 13G/A

ANDERSEN GROUP INC

Class A common stock, par value $0.0001 per share · CUSIP: 033853102

Event date: 2026-02-28

Reporting persons may disclose overlapping interests. Their amounts are shown individually and are not added into a filing total.

Filing-level shares

Unavailable

Percent of class

Unavailable

• BROWN ADVISORY INC

  Shares: 2,946,522 · Class: 23.29%

• BROWN INVESTMENT ADVISORY & TRUST CO

  Shares: 12,694 · Class: 0.1%

• BROWN ADVISORY LLC

  Shares: 2,925,137 · Class: 23.12%

• SIGNATURE FINANCIAL MANAGEMENT, INC.

  Shares: 1,112 · Class: 0.01%

• BROWN ADVISORY LTD

  Shares: 7,579 · Class: 0.06%

Amounts are as disclosed in this filing. Schedule type alone does not establish investment intent.