Moleculin Biotech files for best-efforts offering of up to 4.57M shares at $2.19, targeting $9.1M net

Up to 4,566,210 shares of our common stock on a “best efforts” basis based on an assumed public offering price of $2.19 per share and accompanying common warrants, which was the closing price of our common stock as reported on Nasdaq on July 27, 2026.

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, pre-funded warrants to purchase 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.

We are also offering common warrants to purchase up to 13,698,630 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 assumed initial exercise price of $2.19 per share of common stock (or 100% of the combined offering price).

Common stock outstanding immediately before this offering

5,336,350 shares

Common stock outstanding immediately after this offering

9,902,560 shares, based on an assumed public offering price of $2.19 per share and accompanying common warrants, which was the closing price of our common stock as reported on Nasdaq on July 27, 2026, and assuming full exercise of the pre-funded warrants and assuming no exercise of the common warrants.

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.

The interim analysis, conducted on a full intent-to-treat basis with no patient exclusions, showed complete remission (CR) rates of 43% and 36% in the two Annamycin dose arms (190 mg/m² and 230 mg/m², respectively, each in combination with high-dose cytarabine), compared with 12% in the control arm, and composite complete remission (CRc) rates of 50% and 57% in the respective Annamycin arms compared with 29% in the control arm.

The trial's Independent Data Monitoring Committee (iDMC) reviewed the interim data and unanimously concluded that, although the results did not reach statistical significance, there was a strong numeric trend favoring both Annamycin treatment arms over the control arm on the primary CR endpoint, and that the data supported continuing the trial with both dose arms.

We will require significant additional financing, for which we currently have no commitments, to continue funding our clinical trials, including MIRACLE.

We estimate that the net proceeds from the offering will be approximately $9.1 million, assuming a public offering price of $2.19 per share of common stock and related common warrants (which is equal to the last reported sale price per share of our common stock on the Nasdaq Capital Market, on July 27, 2026), and the sale of all the securities offered under this prospectus, after deducting the placement agent fees and estimated offering expenses payable by us.

We may only receive additional proceeds from the exercise of the common warrants issuable in connection with this offering if the Warrant Stockholder Approval is obtained and, if such common warrants are exercised in full for cash, the additional gross proceeds will be approximately $30.0 million. If the common warrants are exercised in full for cash at the floor price of $0.438 per share, the additional gross proceeds from this offering will be approximately $6.0 million.

However, because this is a “best efforts” offering and there is no minimum offering amount required as a condition to the closing of this offering, the actual offering amount, the placement agent’s fees and net proceeds to us are not presently determinable and may be substantially less than the maximum amounts set forth on the cover page of this prospectus.

Based on the assumed public offering price set forth above, we estimate that our net proceeds from the sale of 75%, 50% and 25% of the securities offered in this offering would be approximately $6.8 million, $4.5 million and $2.1 million, respectively, assuming no sale of any pre-funded warrants or exercise of any common warrants, and 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.

Dilution in net tangible book value per share to new investors

$ 0.87

Each $0.10 increase (decrease) in the assumed public offering price of $2.19 per share, would increase (decrease) our as adjusted net tangible book value per share by $0.61 and $0.52, respectively, and would increase (decrease) dilution per share to new investors in this offering by $0.05 and ($0.05), respectively

Each increase (decrease) of 1,000,000 shares offered by us would increase (decrease) our as adjusted net tangible book value per share by $0.65 and $0.47, respectively, and the dilution per share to new investors purchasing securities in this offering by $0.08 and ($0.10), respectively

The above discussion is based on 5,336,350 shares of our common stock outstanding as of March 31, 2026

12,441,965 shares of common stock underlying outstanding warrants at a weighted average exercise price of $2.52 per share

During 2025, we received notices that we were not in compliance with Nasdaq Listing Rule 5550(b) (1) (the “Equity Rule”), which requires that we maintain a minimum of $2.5 million in stockholders’ equity, and Nasdaq Listing Rule 5550(a) (2), which related to the bid price for our common stock being below the minimum $1.00 per share (the “Bid Price Rule”).

The common warrants provide that in the event of a “Fundamental Transaction” (as defined in the related warrant agreement, which generally includes any merger with another entity, the sale, transfer or other disposition of all or substantially all of our assets to another entity, or the acquisition by a person of more than 50% of our common stock), each common warrant holder will have the right at any time prior to the consummation of the Fundamental Transaction to require us to repurchase the common warrant for a purchase price in cash equal to the Black-Scholes value (as calculated under the warrant agreement) of the then remaining unexercised portion of such common warrant on the date of such Fundamental Transaction, which may materially adversely affect our financial condition and/or results of operations and may prevent or deter a third party from acquiring us.

Our Series G warrants and Series H warrants, which combined represent the potential issuance of 8,978,779 shares of common stock, provide that if, while such warrants are outstanding, we sell any common stock and/or common stock equivalents other than in connection with certain exempt issuances, at a purchase price per share less than the exercise price of the warrants in effect immediately prior to such sale, then immediately after such sale the exercise price of the Series G warrants and/or Series H warrants then in effect will be reduced to an amount equal to the new issuance price, subject to floor prices of $1.326 and $0.962, respectively.

This is a “best efforts” offering. No minimum amount of securities is required to be sold, and we may not raise the amount of capital we believe is required for our business plans, including our near-term business plans.

If we complete the maximum offering hereunder, of which there is no assurance, we believe that the net proceeds from this offering will satisfy our capital needs into the first quarter of 2027 under our current business plan.