GT Biopharma's SEC filings document the regulatory record of a Delaware clinical-stage immuno-oncology company developing TriKE® natural killer cell engager candidates. Registration statements describe securities offerings, Rule 415 offering status, issuer filer status and capital-structure information tied to common stock and preferred-stock instruments.
Current reports cover financial results, material clinical research agreements for GTB-5550, Nasdaq listing-compliance notices, and accounting conclusions involving Series L 10% Convertible Preferred Stock and related purchase rights. Other disclosures address waivers of preferred-stock redemption rights and non-reliance determinations for previously issued interim financial statements.
GT Biopharma, Inc. is registering up to 13,502,835 shares of common stock for resale by selling stockholders. The shares include stock issuable upon conversion of Series M and Series L preferred stock, stock issuable upon exercise of related warrants, and dividend shares already issued.
GT Biopharma will receive no proceeds from selling-stockholder resales. It may receive proceeds from cash exercises of warrants or purchases under the Series M or Series L Greenshoe Rights, intended for working capital and general corporate purposes. The company reports substantial doubt about its ability to continue as a going concern; without additional financing, it may have to delay, reduce, or eliminate discretionary spending. Nasdaq notified the company on September 22, 2026 that it had regained compliance with the $1.00 Minimum Bid Price Requirement after a closing bid above $1.00 per share for at least ten consecutive business days.
GT Biopharma, Inc. (GTBP) asks stockholders at a November 11, 2026 special meeting to vote on four proposals: remove obsolete preferred-stock provisions; allow the Board, subject to approval, to increase authorized common shares from 25,000,000 to 250,000,000 by November 11, 2027; approve issuance of 19.99% or more of outstanding common shares under the Series M transaction; and allow adjournment if needed. The Board recommends FOR each proposal.
The September 14, 2026 securities purchase agreement, amended September 18, provides for up to 8,611.111 Series M preferred shares and warrants, with $8,611,111.11 aggregate stated value for a $7,750,000 purchase price. It also provides Greenshoe Rights for Series M purchases with up to $34,675,615 aggregate stated value at an aggregate purchase price of $31,208,054, subject to adjustments. Approval of Proposal 3 would remove the 19.99% ownership limitation and 360,695-share Exchange Cap for covered securities. Based on 2,061,052 shares outstanding as of September 30, 2026, the company estimates investors would hold approximately 44% of voting power after conversion alone, or approximately 61% after conversion and cash exercise of all Common Stock Warrants. The company discloses that additional share issuance could dilute earnings per share and voting rights.
GT Biopharma, Inc. is registering up to 13,502,835 shares of common stock for resale by selling stockholders. The shares include common stock issuable upon conversion of Series M and Series L preferred stock, upon warrant exercise, and shares issued as preferred-stock dividends. The company will not receive proceeds from selling-stockholder sales, but may receive proceeds from cash warrant exercises or purchases under Series M or Series L Greenshoe Rights.
GT Biopharma reported 2,061,052 shares of common stock outstanding as of October 9, 2026, and $9,706,500 in gross proceeds before expenses from Series L Greenshoe Rights exercised to date, intended for working capital and general corporate purposes. The company states that substantial doubt has been raised about its ability to continue as a going concern and that additional financing on acceptable terms is not assured.
GT Biopharma, Inc. asks stockholders to vote at a November 11, 2026 special meeting on four proposals: remove charter provisions for preferred-stock series no longer outstanding; raise authorized Common Stock from 25,000,000 to 250,000,000 shares; approve issuances under a securities purchase agreement; and permit adjournment if needed for a quorum or more votes. The board recommends “FOR” all four.
The charter changes require stockholder approval, and the board may elect whether and when to implement them by November 11, 2027. The company says future share issuances could dilute earnings per share and voting rights. Proposal 3 concerns Series M Preferred Stock conversions and warrant exercises beyond the 19.99% Beneficial Ownership Limitation or 360,695-share Exchange Cap.
The September 14, 2026 transaction has an aggregate purchase price of $7,750,000 for Series M Preferred Stock and warrants, with an aggregate stated value of $8,611,111.11. If Proposal 3 passes, the private-placement investors could hold approximately 44% of voting power after full preferred-stock conversion, or approximately 61% if all Common Stock Warrants are also exercised solely for cash, based on 2,061,052 shares outstanding as of September 30, 2026.
GT Biopharma, Inc. reported $7,750,000 sold and $31,208,054 remaining to be sold in the offering. It lists September 14, 2026 as the date of first sale and reports $0 in finders’ fees.
GT Biopharma, Inc. (GTBP) reported that Nasdaq notified it on September 22, 2026, that it had regained compliance with the $1.00-per-share minimum bid price requirement for continued listing. Its common stock maintained a closing bid price above $1.00 per share for at least ten consecutive business days, meeting Nasdaq’s stated requirement. The company had received an initial deficiency notice after its stock closed below $1.00 per share for 30 consecutive business days. On May 20, 2026, Nasdaq granted an additional 180-calendar-day compliance period through November 16, 2026.
GT Biopharma, Inc. (GTBP) amended its previously announced private placement of Series M 10% Convertible Preferred Stock and related warrants. A new purchaser joined and the parties signed a First Amendment to the Securities Purchase Agreement on September 18, 2026, increasing the preferred issuance to 8,611.111 shares with an aggregate stated value of $8,611,111.11 for an aggregate purchase price of $7,750,000.
The amendment also confirms that each purchaser has Greenshoe Rights to buy additional preferred stock with aggregate stated value of up to $34,675,615 for an aggregate purchase price of $31,208,054, allocated based on each purchaser’s original subscription amount. The securities are being sold in a private placement under Rule 506(b) of Regulation D.
A joinder brings the new purchaser into the existing Registration Rights Agreement, under which GT Biopharma agrees to register the resale of common stock issuable upon conversion of the preferred and exercise of the warrants within specified SEC filing and effectiveness timelines. The company also filed a Certificate of Increase in Delaware, raising the designated Series M preferred shares from 41,778 to 43,287.
GT Biopharma, Inc. (GTBP) has a new large shareholder disclosure, as RainForest Partners LLC reported beneficial ownership of 180,258 shares of common stock on a Schedule 13G. This represents 9.99% of the outstanding common stock, giving RainForest sole voting and dispositive power over these shares.
The percentage is calculated based on 1,804,380 shares outstanding as of September 8, 2026, as referenced in the filing. RainForest’s holdings are subject to a contractually stipulated 9.99% ownership restriction, and the filing states that full conversion or exercise of RainForest’s securities would exceed this limit.
GT Biopharma, Inc. (GTBP) entered into a private placement on September 14, 2026 to sell up to 8,277.778 shares of Series M 10% Convertible Preferred Stock with an aggregate stated value of $8,277,778 for an aggregate purchase price of $7,450,000, together with common stock warrants. Each purchaser also receives Greenshoe Rights to buy additional preferred stock with an aggregate stated value of $33,333,333 for $30,000,000, plus additional vesting warrants.
The preferred stock is convertible into common stock at an initial price of $6.10 per share and carries cumulative dividends of 10% per annum until September 13, 2027, rising to 12% thereafter, payable quarterly in cash or stock. Common and vesting warrants have a $6.10 exercise price and a five-year term, and the preferred and warrants include full ratchet price protection, with a potential Nasdaq-driven floor price of $1.282 on certain adjustments. GT Biopharma agreed to register the resale of underlying shares on a tight timetable, with 1.5% liquidated damages of each purchaser’s subscription amount plus interest at the prime rate plus 12% if deadlines and payments are missed, and entered related voting and lockup agreements with officers and directors.