mbrx20260731_424b5.htm

424B5 1 mbrx20260731_424b5.htm FORM 424B5 mbrx20260731_424b5.htm

Filed Pursuant to Rule 424(b)(5)
Registration No. 333-297776

PROSPECTUS

Moleculin Biotech, Inc.

Up to 11,088,334 Shares of Common Stock

Up to 1,288,333 Pre-Funded Warrants to Purchase up to 1,288,333 Shares of Common Stock

Up to 37,130,001 Common Warrants to Purchase up to 37,130,001 Shares of Common Stock

Up to 38,418,334 Shares of Common Stock underlying the Pre-Funded Warrants and Common Warrants

This is a reasonable best efforts public offering of up to 11,088,334 shares of our common stock, together with up to 37,130,001 Series I common warrants to purchase an aggregate of up to 37,130,001 shares of common stock (“common warrants”) at a combined public offering price of $0.75 per share and common warrants.

Each share of common stock is being offered together with three common warrants, each to purchase one share of common stock. The common warrants will be exercisable beginning on the closing date of this offering at an exercise price of $0.75 per share and will expire five years from the initial exercise date.

The shares of common stock and accompanying common warrants will be separately issued and will be immediately separable upon issuance but will be purchased together in this offering. This prospectus also covers the shares of common stock issuable upon exercise of the common warrants sold in this offering.

We are also offering 1,288,333 pre-funded warrants to purchase 1,288,333 shares of common stock to those purchasers, whose purchase of shares of common stock in this offering would result in the purchaser, together with its affiliates and certain related parties, beneficially owning more than 4.99% (or, at the election of the purchaser, 9.99%) of our outstanding common stock immediately following the consummation of this offering in lieu of the shares of our common stock that would result in ownership in excess of 4.99% (or, at the election of the purchaser, 9.99%). Each pre-funded warrant will be exercisable for one share of common stock at an exercise price of $0.001 per share. Each pre-funded warrant is being offered together with the same common warrants, each to purchase one share of common stock described above being offered with each share of common stock. The purchase price of each pre-funded warrant will equal the combined public offering price per share of common stock and common warrants being sold in this offering, less the $0.001 per share exercise price of each such pre-funded warrant. Each pre-funded warrant will be immediately exercisable upon issuance and will expire when exercised in full. The pre-funded warrants and accompanying common warrants will be separately issued and will be immediately separable upon issuance but will be purchased together in this offering. This prospectus also covers the shares of common stock issuable from time to time upon the exercise of the pre-funded warrants offered hereby.

There is no established public trading market for the pre-funded warrants or common warrants, and we do not expect a market to develop. We do not intend to apply for listing of the pre-funded warrants or common warrants on any securities exchange or other nationally recognized trading system. Without an active trading market, the liquidity of the pre-funded warrants and common warrants will be limited.

	Per Share and Common Warrants		Per Pre-Funded Warrant and Common Warrants		Total
Public offering price	$	0.75	$	0.749	$	9,281,211.92
Placement Agent fees⁽¹⁾	$	0.049	$	0.049	$	603,278.77
Proceeds to us, before expenses⁽²⁾	$	0.701	$	0.700	$	8,677,933.15

ABOUT THIS PROSPECTUS	1
PROSPECTUS SUMMARY	2
THE OFFERING	4
RISK FACTORS	6
CAUTIONARY NOTE REGARDING FORWARD-LOOKING STATEMENTS	9
USE OF PROCEEDS	11
DILUTION	12
STOCK OWNERSHIP OF CERTAIN BENEFICIAL OWNERS AND MANAGEMENT	13
DESCRIPTION OF CAPITAL STOCK	14
DESCRIPTION OF COMMON WARRANTS	17
DESCRIPTION OF PRE-FUNDED WARRANTS	19
PLAN OF DISTRIBUTION	20
INCORPORATION OF CERTAIN INFORMATION BY REFERENCE	21
WHERE YOU CAN FIND MORE INFORMATION	22
LEGAL MATTERS	22
EXPERTS	22

Common stock we are offering		Up to 11,088,334 shares of our common stock on a “best efforts” basis at a public offering price of $0.75 per share and accompanying common warrants.

Pre-funded warrants we are offering		We are also offering to certain purchasers whose purchase of shares of common stock in this offering would otherwise result in the purchaser, together with its affiliates and certain related parties, beneficially owning more than 4.99% (or, at the election of the purchaser, 9.99%) of our outstanding common stock immediately following the closing of this offering, the opportunity to purchase, if such purchasers so choose, up to 1,288,333 pre-funded warrants to purchase up to 1,288,333 shares of common stock, in lieu of shares of common stock that would otherwise result in any such purchaser’s beneficial ownership exceeding 4.99% (or, at the election of the purchaser, 9.99%) of our outstanding common stock. Each pre-funded warrant is exercisable for one share of our common stock. The purchase price of each pre-funded warrant and accompanying common warrants is equal to the price at which a share of common stock and accompanying common warrants are being sold to the public in this offering, minus $0.001, and the exercise price of each pre-funded warrant is $0.001 per share. The pre-funded warrants are exercisable immediately and may be exercised at any time until all of the pre-funded warrants are exercised in full. This offering also relates to the shares of common stock issuable upon exercise of any pre-funded warrants sold in this offering.

Common warrants we are offering		We are also offering common warrants to purchase up to 37,130,001 shares of our common stock. Each share of common stock is being offered together with three common warrants, each to purchase one share of common stock. Each common warrant has an initial exercise price of $0.75 per share of common stock. The common warrants will become exercisable beginning on the closing date of this offering and will expire five years from the initial exercise date. The common warrants include certain mechanisms, including certain anti-dilution provisions and other standard adjustment provisions. To better understand the terms of the common warrants, you should carefully read the “Description of Common Warrants” section of this prospectus. You should also read the form of the common warrant, which is filed as an exhibit to the registration statement of which this prospectus forms a part. The shares of common stock and pre-funded warrants, and the accompanying common warrants can only be purchased together in this offering but will be issued separately and will be immediately separable upon issuance. This prospectus also relates to the offering of the shares of common stock issuable upon exercise of the common warrants and the pre-funded warrants.

Term of the offering		This offering will terminate on August 14, 2026, unless we decide to terminate the offering (which we may do at any time in our discretion) prior to that date.

Common stock outstanding immediately before this offering		7,100,713 shares

Common stock outstanding immediately after this offering		18,189,047 shares, or 19,477,380 shares assuming full exercise of the 1,288,333 pre-funded warrants and, in each case, assuming no exercise of the common warrants.

Use of proceeds		We estimate that the net proceeds from this offering will be approximately $8.5 million, after deducting the placement agent fees and estimated offering expenses payable by us. We intend to use the net proceeds to advance Annamycin through clinical development and for working capital. See “Use of Proceeds” for additional information.

Insider participation		Certain of our officers and directors have agreed to purchase an aggregate of 1,319,998 shares together with 3,959,994 common warrants in this offering on the same terms as the other investors participating in the offering.

Reasonable best efforts offering		We have agreed to offer and sell the securities offered hereby to the purchasers through the placement agent. The placement agent is not required to buy or sell any specific number or dollar amount of the securities offered hereby, but will use its reasonable best efforts to solicit offers to purchase the securities offered by this prospectus. See “Plan of Distribution” on page 20 of this prospectus.

Risk factors		An investment in our securities involves a high degree of risk. See “Risk Factors” beginning on page 6 of this prospectus and the other information included and incorporated by reference in this prospectus for a discussion of the risk factors you should carefully consider before deciding to invest in our securities.

Nasdaq listing symbol		Our common stock is listed on the Nasdaq Capital Market under the symbol “MBRX.” There is no established trading market for the common warrants or pre-funded warrants and we do not expect a market to develop. In addition, we do not intend to apply for the listing of the common warrants or pre-funded warrants on any national securities exchange or other trading market. Without an active trading market, the liquidity of the common warrants and pre-funded warrants will be limited.

Public offering price per share and accompanying common warrants	$	0.75
Historical net tangible book value per share at March 31, 2026	$	0.76
Decrease in net tangible book value per share to the existing stockholders attributable to this offering	$	0.05
As adjusted net tangible book value per share after this offering	$	0.71
Dilution in net tangible book value per share to new investors	$	0.04

	As of June 30, 2026
	Shares beneficially owned			Percent of Class (1)
Name of Beneficial Owner
Walter V. Klemp		286,469	(2)		3.9	%
Jonathan P. Foster		114,875	(3)		1.6	%
Donald Picker		2,127	(4)	Less than 1%
Robert George		734	(5)	Less than 1%
Michael Cannon		616	(6)	Less than 1%
John Climaco		609	(6)	Less than 1%
Elizabeth Cermak		588	(6)	Less than 1%
Joy Yan		561	(6)	Less than 1%
*Directors and Executive Officers as a Group (8* *persons)*		406,579	(7)		5.4	%

*5% Holders*
None