Series L investors waive redemption rights at GT Biopharma (GTBP)

Rhea-AI Filing Summary

GT Biopharma, Inc. reports that all holders of its Series L 10% Convertible Preferred Stock have agreed to waive their contractual rights to redemption under Section 10 of the applicable certificate of designations. This means those preferred holders no longer have the ability to require the company to redeem the Series L shares for cash as previously provided.

The change modifies the rights of the Series L preferred stockholders and reduces a potential future cash obligation for the company, while leaving other terms to be interpreted from the full waiver document attached as an exhibit.

Positive

• All Series L preferred holders waive redemption rights, removing a contractual mechanism that could have forced significant cash redemptions and easing potential liquidity pressure.

Negative

• None.

Insights

Capital structure and credit risk analyst

Waiver removes a potential cash drain from Series L preferred stock.

GT Biopharma obtained waivers from all holders of its Series L 10% Convertible Preferred Stock, eliminating their contractual rights to redemption under Section 10 of the certificate of designations. Redemption rights can create significant future cash obligations if triggered, so removing them alters the risk profile associated with this class of securities.

This change reduces the prospect of forced cash outflows tied specifically to Series L redemptions, which can be important for liquidity management in a development-stage or cash‑sensitive business. The broader impact on common shareholders and on the valuation of the preferred shares will depend on the remaining terms of the Series L and how investors view the trade‑off between yield, conversion features, and now the absence of redemption rights.

The waiver is documented in a form attached as Exhibit 10.1, indicating a standardized agreement across holders. Subsequent disclosures in future reports may give more context on how this modification interacts with the company’s overall financing strategy and capital needs.

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UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 OR 15(d) of The Securities Exchange Act of 1934

Date of Report: September 25, 2025

(Date of earliest event reported)

GT Biopharma, Inc.

(Exact name of registrant as specified in its charter)

Delaware

(State or other Jurisdiction of Incorporation)

1-40023		94-1620407
(Commission File Number)		(IRS Employer Identification No.)

N/A¹

(Address of Principal Executive Offices and zip code)

(415) 919-4040

(Registrant’s telephone number, including area code)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of registrant under any of the following provisions:

☐	Written communications pursuant to Rule 425 under the Securities Act (17 CFR 230.425)
☐	Soliciting material pursuant to Rule 14a-12(b) under the Exchange Act (17 CFR 240.14a-12(b))
☐	Pre-commencement communications pursuant to Rule 14d-2(b) under the Exchange Act (17 CFR 240.14d-2(b))
☐	Pre-commencement communications pursuant to Rule 13e-4(c) under the Exchange Act (17 CFR 240.13e-4(c))

Securities registered pursuant to Section 12(b) of the Act:

Title of each Class		Trading Symbol(s)		Name of each Exchange on which registered
Common stock, $0.001 par value		GTBP		The Nasdaq Stock Market LLC

Indicate by check mark whether the registrant is an emerging growth company as defined in Rule 405 of the Securities Act of 1933 (§230.405 of this chapter) or Rule 12b-2 of the Securities Exchange Act of 1934 (§240.12b-2 of this chapter).

Emerging growth company ☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act. ☐

¹ Effective as of July 1, 2024, the Company became a fully remote company. We do not maintain a principal executive office. For purposes of compliance with applicable requirements of the Securities Act of 1933, as amended, and the Securities Exchange Act of 1934, as amended, any stockholder communication required to be sent to the Company’s principal executive offices may be directed to 505 Montgomery Street, 10th Floor, San Francisco, California 94111, or by email to auditcommittee@gtbiopharma.com.

Item 3.03 Material Modification to Rights of Security Holders.

As previously disclosed, on each of September 17, 2025, September 18, 2025 and September 23, 2025, certain of the holders of GT Biopharma, Inc.’s Series L 10% Convertible Preferred Stock (the “Series L Preferred Stock”) provided a waiver (the “Waiver”) to the Certificate of Designation of Preferences, Rights and Limitations of Series L 10% Convertible Preferred Stock (the “Certificate of Designations”). On September 25, 2025, an additional holder of Series L Preferred Stock provided a Waiver. Pursuant to the Waiver, all Series L Preferred Stockholders have agreed to waive the rights to redemption set forth in Section 10 of the Certificate of Designations.

The foregoing description of the Waiver does not purport to be complete and is qualified in its entirety by reference to the full text of the Waiver, which is attached hereto as Exhibit 10.1 and is incorporated herein by reference.

Item 9.01 Financial Statements and Exhibits.

(d) Exhibits.

Exhibit Number		Description
10.1		Form of Waiver (incorporated by reference to exhibit 10.1 of GT Biopharma, Inc.’s Form 8-K filed with the Securities and Exchange Commission on September 23, 2025)
104		Cover Page Interactive Data File, formatted in Inline XBRL

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the Registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

	GT BIOPHARMA, INC.
Date: September 26, 2025	By:	/s/ Alan Urban
		Alan Urban
		Chief Financial Officer

FAQ

What did GT Biopharma (GTBP) change about its Series L preferred stock?

GT Biopharma disclosed that all holders of its Series L 10% Convertible Preferred Stock agreed to a waiver eliminating their rights to redemption under Section 10 of the certificate of designations.

How many GT Biopharma Series L preferred holders agreed to the waiver?

The company reports that, after an additional holder joined on September 25, 2025, all Series L 10% Convertible Preferred Stockholders had provided waivers of their redemption rights.

What rights are Series L preferred holders giving up at GT Biopharma?

They are waiving the rights to redemption specified in Section 10 of the Certificate of Designation of Preferences, Rights and Limitations of Series L 10% Convertible Preferred Stock.

Why is the waiver of redemption rights significant for GTBP investors?

Redemption rights can require a company to pay cash to redeem preferred shares; waiving those rights removes that specific potential cash obligation tied to the Series L preferred stock.

Where can investors read the full terms of the GT Biopharma Series L waiver?

The company attached the form of waiver as Exhibit 10.1, incorporating it by reference, so investors can review the full text in that exhibit.

Does the waiver affect other terms of GT Biopharma’s Series L preferred stock?

The disclosure highlights the waiver of redemption rights under Section 10; other terms remain as defined in the certificate of designations and the waiver document itself.