Andersen Group Inc. S-1Registration Statements (S-1 / prospectus)

Risk Factors

Risk Factors See the section titled “Risk Factors” herein and in our 2025 Form 10-K, which is incorporated by reference in this prospectus, for a discussion of factors you should carefully consider before deciding to invest in our Class A common stock. Certain U.S. federal income tax consequence to non-U.S. holders For a discussion of certain U.S. federal income tax consequences that may be relevant to non-U.S. stockholders, see the section titled “Material U.S. Federal Tax Consequences to Non-U.S. Holders of Our Common Stock.” NYSE trading symbol “ANDG” The number of shares of our Class A common stock and Class B common stock to be outstanding after this offering, as well as our presentations of economic and voting power in this prospectus, are based on the shares of common stock of Andersen Group Inc. and membership interests of AT Umbrella LLC outstanding as of June 30, 2026, and exclude: • 141,071 shares of Class A common stock issued in connection with certain acquisitions and business combinations since June 30, 2026; • 102,000 shares of Class A common stock issued upon redemption of 102,000 Class X Aggregator units held by certain stockholders for Class X Umbrella Units (and the cancellation of paired shares of Class B common stock); • 99,415,168 shares of Class A common stock reserved for issuance upon the redemption or exchange of Class X Umbrella Units and LTIP Units (together with corresponding shares of our Class B common stock) as of June 30, 2026; • the cancellation of 40,000 Class X Umbrella Units (and the cancellation of paired Class X Aggregator Units and shares of Class B common stock) since June 30, 2026; • 12,290,828 shares of Class A common stock reserved for future issuance under our 2025 Equity Incentive Plan (2025 Plan) as of June 30, 2026; and • 5,103,260 shares subject to restricted stock units (RSUs) outstanding under our 2025 Plan as of June 30, 2026. 18 Table of Contents Our 2025 Plan also provides for automatic annual increases in the number of shares reserved under this plan, as more fully described in “Equity Compensation Plan Information” in our Proxy Statement incorporated by reference in this prospectus. Unless otherwise indicated, this prospectus reflects and assumes that all outstanding LTIP Units will be converted on a one-to-one basis. 19 Table of Contents SUMMARY CONSOLIDATED FINANCIAL AND OTHER DATA The following tabl