Amendment to Quarterly Report (Form 10-Q/A)

GT Biopharma, Inc. (the "Company") is filing this Quarterly Report on Form 10-Q/A, Amendment No. 1 (the "Quarterly Report on Form 10-Q/A") to amend and restate its Quarterly Report on Form 10-Q for the fiscal quarter ended June 30, 2025 filed with the Securities and Exchange Commission on May 15, 2025 (the "Original Report"). The purpose of this Quarterly Report on Form 10-Q/A is to restate the Company's balance sheet, statement of operations, and statement of cash flows to correct of material errors as indicated below.

Restatement Background

On March 1, 2026, the audit committee of the Company's board of directors, after discussion with the Company's management, concluded that the Company's interim quarterly financial statements as originally reported in the Company's Quarterly Reports on Form 10-Q for the quarterly period ended June 30, 2025, should no longer be relied upon. The determination resulted from errors identified in the course of preparing for the audit of the Company's December 31, 2025 financial statements. Upon reevaluation of Greenshoe Rights (as defined below) connected to the Series L Convertible Preferred Stock (as defined below) issued in May 2025, management determined that the Greenshoe Rights met the criteria for liability classification in accordance with ASC 480. Accordingly, the Greenshoe Rights required classification as a liability and marked to market at each reporting date as required under GAAP.

Restatement Adjustments

The Company inadvertently did not classify the Greenshoe Rights as a liability, which led to accounting adjustments to correct the errors identified (see Note 2 - Restatement of Quarterly Financial Statements (Unaudited)). The Company is restating the unaudited condensed financial statements and related information for the quarter ended June 30, 2025, in this Quarterly Report on Form 10-Q/A.

Internal Control Considerations

In connection with the restatement of the financial statements for the quarter ended June 30, 2025, the Company has concluded its disclosure controls and procedures as of June 30, 2025, were ineffective due to the errors described above. Please refer to Part I, Item 4 of this Form 10-Q/A.