SEC Form 424B5 filed by Windtree Therapeutics Inc.

Table of Contents

Filed Pursuant to Rule 424(b)(5)

Registration No. 333-284976

PROSPECTUS

Up to 31,247,383 Shares of Common Stock

This prospectus relates to (i) the offer and resale or other disposition from time to time by certain of the selling stockholders identified in this prospectus of (a) up to 8,053,565 shares of our common stock (the “Conversion Shares”), par value $0.001 per share, issuable upon the conversion of shares of our Series C convertible preferred stock, par value $0.001 per share (the “Series C Preferred Stock”), and (b) up to 440,583 shares (the “Subject Warrant Shares”) of our common stock issuable upon the exercise of certain warrants (the “Subject Warrants”); and (ii) the offer and resale or other disposition from time to time by certain of the selling stockholders identified in this prospectus of up to 919,132 shares of our common stock (the “Subject Note Shares”) that may be issued upon the conversion of the 20% OID Senior Secured Promissory Notes (the “Subject Notes”) that we issued on April 4, 2025. This prospectus also relates to the resale from time to time of shares of our common stock issued pursuant to the equity line of credit (“ELOC”) established under the a common stock purchase agreement (the “ELOC Purchase Agreement”) that we entered into with Seven Knots, LLC (“Seven Knots”) on June 26, 2024 of our common stock in an offering amount of up to $23.8 million, representing 21,834,103 shares of common stock based on the average of the high and low reported prices of our common stock as reported on The Nasdaq Capital Market on April 17, 2025, of $1.149 less a 5% discount, that we may issue to Seven Knots under the ELOC Purchase Agreement (the “ELOC Shares”).

We are registering the resale of the shares of common stock covered by this prospectus pursuant to the selling stockholders’ registration rights under (i) the Registration Rights Agreement, dated July 22, 2024, by and among us and the PIPE Tranche I Investors (as defined below), (ii) the Registration Rights Agreement, dated July 29, 2024, by and among us and the PIPE Tranche II Investors (as defined below), (iii) the Subject Notes, and (iv) the ELOC Purchase Agreement.

We will not receive any proceeds from the sale by the selling stockholders of their shares of common stock. However, we may receive (i) up to approximately $0.2 million from the exercise of the Subject Warrants for cash; and (ii) up to $23.8 million from sales of ELOC Shares to Seven Knots. We have received aggregate gross proceeds of $11.2 million from the issuance of 342,900 shares of common stock under the ELOC Purchase Agreement through the date of this prospectus. We have agreed to bear the expenses in connection with the registration of the resale of the shares of common stock to be offered by this prospectus by the selling stockholders except for any underwriting discounts and commissions or transfer taxes relating to the sale of common stock, which will be borne by the selling stockholders.

Our registration of the shares on behalf of the selling stockholders does not mean that any of the selling stockholders will offer or sell any of their shares of common stock. We cannot predict when, or in what amounts, the selling stockholders may sell their shares of common stock. Sales of the shares of common stock by the selling stockholders may occur in one or more transactions at fixed prices, at market prices prevailing at the time of sale, at prices related to prevailing market prices, at negotiated prices, and/or at varying prices determined at the time of sale. The selling stockholders may sell their shares of common stock directly or to or through underwriters, broker-dealers or agents, who may receive compensation in the form of discounts, concessions or commissions from the selling stockholders, the purchasers of the shares, or both. We provide more information about how the selling stockholders may sell or otherwise dispose of their shares of common stock in the section of this prospectus titled “Plan of Distribution.”

Our common stock is traded on The Nasdaq Capital Market under the symbol “WINT”. The last reported sale price of our common stock on The Nasdaq Capital Market on April 24, 2025 was $1.17 per share.

On February 14, 2025, we filed a certificate of amendment to the Company’s Amended and Restated Certificate of Incorporation with the Secretary of State of the State of Delaware to effectuate a 1-for-50 reverse stock split (the “Reverse Stock Split”) of the outstanding shares of the Company’s common stock. Our stockholders previously approved the Reverse Stock Split and granted the Company’s board of directors the authority to determine the exact split ratio and when to proceed with the Reverse Stock Split at the Company’s special meeting of stockholders held on February 3, 2025. The Reverse Stock Split became effective on February 20, 2025 at 5:00 p.m., Eastern Time and our common stock began trading on The Nasdaq Capital Market on a Reverse Stock Split-adjusted basis on February 21, 2025 at market open under the existing ticker symbol, “WINT.” Pursuant to the Reverse Stock Split, every 50 shares of the Company’s issued and outstanding common stock was combined into one share of common stock. The par value and other terms of the common stock were not affected by the Reverse Stock Split. No fractional shares were issued as a result of the Reverse Stock Split.

All financial information, share numbers, option numbers, warrant numbers, other derivative security numbers, and exercise prices appearing in this prospectus have been adjusted to give effect to the Reverse Stock Split, except where otherwise stated.

We are a “smaller reporting company” as defined under the federal securities laws and, as such, have elected to comply with certain reduced public company reporting requirements for this prospectus and the documents incorporated by reference herein.

Investing in our common stock involves a high degree of risk. You should consider carefully the “Risk Factors” beginning on page 9 of this prospectus and under similar headings in any amendment or supplement to this prospectus and in any other documents incorporated by reference into this prospectus, before purchasing any of the shares offered by this prospectus.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or determined if this prospectus is truthful or complete. Any representation to the contrary is a criminal offense.

The date of this prospectus is April 25, 2025.

TABLE OF CONTENTS

ABOUT THIS PROSPECTUS

The registration statement we filed with the U.S. Securities and Exchange Commission (the “SEC”) includes exhibits that provide more detail of the matters discussed in this prospectus. You should read this prospectus, the related exhibits filed with the SEC, and the documents incorporated by reference herein before making your investment decision. You should rely only on the information provided in this prospectus and the documents incorporated by reference herein or any amendment or supplement thereto.

You should not assume that the information contained in this prospectus or any related free writing prospectus is accurate on any date subsequent to the date set forth on the front of the document or that any information we have incorporated by reference herein or therein is correct on any date subsequent to the date of the document incorporated by reference, even though this prospectus or any related free writing prospectus is delivered, or securities are sold, on a later date. We may amend or supplement this prospectus from time to time by filing amendments or supplements as required. This prospectus contains or incorporates by reference summaries of certain provisions contained in some of the documents described herein, but reference is made to the actual documents for complete information. You should read the entire prospectus, any amendments or supplements, and the information incorporated by reference in this prospectus carefully. All of the summaries are qualified in their entirety by the actual documents. Copies of some of the documents referred to herein have been or will be filed or have been or will be incorporated by reference as exhibits to the registration statement of which this prospectus forms a part, and you may obtain copies of those documents as described in this prospectus under the heading “Where You Can Find More Information.”

You should rely only on the information that we have included or incorporated by reference in this prospectus and any related free writing prospectus that we may authorize to be provided to you. We have not, and the selling stockholders have not, authorized anyone to give any information or to make any representation other than those contained or incorporated by reference in this prospectus or any related free writing prospectus that we may authorize to be provided to you. You must not rely upon any information or representation not contained or incorporated by reference in this prospectus or any related free writing prospectus. This prospectus and any related free writing prospectus do not constitute an offer to sell or the solicitation of an offer to buy any securities other than the registered securities to which they relate, nor do this prospectus or any related free writing prospectus constitute an offer to sell or the solicitation of an offer to buy securities in any jurisdiction to any person to whom it is unlawful to make such offer or solicitation in such jurisdiction.

In addition, while we believe the industry, market and competitive position data included in this prospectus, including the information incorporated by reference herein, is reliable and based on reasonable assumptions, such data involve risks and uncertainties and are subject to change based on various factors. These factors could cause results to differ materially from those expressed in the estimates made by the independent parties or by us.

Unless the context otherwise requires, references in this prospectus to “Windtree,” “Windtree Therapeutics,” the “Company,” “we,” “our,” and “us” refer to Windtree Therapeutics, Inc., a Delaware corporation, and our consolidated subsidiaries.

We use “Windtree Therapeutics,” as our trademark, and we have been granted a trademark or have a trademark application on file with the United States Patent and Trademark Office. All trademarks or trade names referred to in this prospectus and the documents incorporated by reference herein are the property of their respective owners. Solely for convenience, the trademarks and trade names in this prospectus and the documents incorporated by reference herein are referred to without the ® and ™ symbols, but such references should not be construed as any indicator that their respective owners will not assert, to the fullest extent under applicable law, their rights thereto. We do not intend the use or display of other companies’ trademarks and trade names to imply a relationship with, or endorsement or sponsorship of us, by any other companies.

The Offering

Throughout this prospectus, when we refer to the shares of common stock being registered on behalf of the selling stockholders for offer and resale, we are referring to the shares of common stock issued. When we refer to the selling stockholders in this prospectus, we are referring to the selling stockholders identified in this prospectus and, as applicable, their transferees, donees, pledgees, distributes, and other successors-in-interest that may be identified in a supplement to this prospectus or, if required, a post-effective amendment to the registration statement of which this prospectus is a part.

The number of shares of our common stock to be outstanding after this offering is based on 3,652,317 shares of common stock outstanding as of April 24, 2025, and excludes, unless otherwise stated:

Except as otherwise indicated, the information in this prospectus assumes no exercise of the outstanding options or warrants described above.

RISK FACTORS

Investing in our securities involves a high degree of risk. You should carefully consider the risks described below, and those discussed under the section entitled “Risk Factors” contained in our Annual Report on Form 10-K for the year ended December 31, 2024, which is incorporated by reference in this prospectus, and any of our subsequent Quarterly Reports, together with other information in this prospectus, the information and documents incorporated by reference herein, and in any free writing prospectus that we have authorized for use in connection with this offering. These risks and uncertainties are not the only risks and uncertainties we face. Additional risks and uncertainties not currently known to us, or that we currently view as immaterial, may also impair our business, operating results, prospects, or financial condition. If the realization of any of the risks or uncertainties actually occur, our business, financial condition, results of operations and prospects could be materially and adversely affected. In that case, the trading price of our common stock could decline and you might lose all or part of your investment.

Risks Related to This Offering

A sale of a substantial number of shares of common stock by the selling stockholders could cause the price of our common stock to decline.

The shares of common stock covered by this prospectus represent a large number of shares of our common stock, and, following the effectiveness of the registration statement of which this prospectus forms a part, such shares of common stock may be sold by the selling stockholders in the public market without restriction. If the selling stockholders sell, or the market perceives that our stockholders intend to sell for various reasons, substantial amounts of the shares of common stock in the public market, the price of our common stock may decline. Additionally, such conditions may make it more difficult for us to sell equity or equity-related securities in the future at a time and price that we deem reasonable or appropriate.

You may experience future dilution as a result of future equity offerings and other issuances of our securities.

In order to raise additional capital, we may in the future offer additional shares of common stock or other securities convertible into or exchangeable for our common stock prices that may not be the same as the price per share paid by the selling stockholders. We may not be able to sell shares or other securities in any other offering at a price per share that is equal to or greater than the price per share paid by the investors in this offering, and investors purchasing shares or other securities in the future could have rights superior to existing stockholders. The price per share at which we sell additional shares of common stock or securities convertible into shares of common stock in future transactions may be higher or lower than the price per share paid to the selling stockholders. Our stockholders will incur dilution upon exercise of any outstanding stock options, warrants or other convertible securities or upon the issuance of shares of common stock under our stock incentive programs.

Any additional capital raised through the sale of equity or equity-backed securities may dilute our stockholders’ ownership percentages and could also result in a decrease in the market value of our equity securities.

The terms of any securities issued by us in future capital transactions may be more favorable to new investors, and may include preferences, superior voting rights and the issuance of warrants or other derivative securities, which may have a further dilutive effect on the holders of any of our securities then outstanding.

We expect to require additional capital in the future in order to pursue our strategic goals, including in order to develop our product candidates. If we do not obtain any such additional financing, it may be difficult to effectively realize our near- and long-term strategic goals and objectives.

Our current cash resources will not be sufficient to fund our research and development efforts for our product candidates, including our lead product candidate, istaroxime. If we cannot secure this additional funding when such funds are required, we may fail to develop our product candidates or be forced to forego certain strategic opportunities.

In addition, we may incur substantial costs in pursuing future capital financing, including investment banking fees, legal fees, accounting fees, securities law compliance fees, printing and distribution expenses and other costs. We may also be required to recognize non-cash expenses in connection with certain securities we issue, such as convertible notes and warrants, which may adversely impact our financial condition.

Future resales and/or issuances of shares of common stock, including pursuant to this prospectus, or the perception that such sales may occur, may cause the market price of our shares to drop significantly.

We have already sold 342,900 ELOC Shares to Seven Knots pursuant to the ELOC Purchase Agreement and may elect, at our sole discretion, to sell from time to time an additional $23.8 million of ELOC Shares to Seven Knots pursuant to the ELOC Purchase Agreement, which may result in the issuance of up to 21,834,103 ELOC Shares based on the average of the high and low reported prices of our common stock as reported on The Nasdaq Capital Market on April 17, 2025, of $1.149 less a 5.0% discount.

Assuming that we issue and sell to Seven Knots such 21,834,103 ELOC Shares, Seven Knots will have acquired a total of 22,177,003 shares of our common stock. Seven Knots may resell all, some or none of such ELOC Shares at any time or from time to time in its discretion and at different prices. Because the shares held by Seven Knots will represent a significant portion of our public float, sales of ELOC Shares to Seven Knots by us could result in substantial dilution to the interests of other holders of shares of our common stock and may result in substantial decreases to the price of our common stock. The actual sales of ELOC Shares or the mere existence of our arrangement with Seven Knots may also make it more difficult for us to sell equity or equity-related securities in the future at a time and at a price that we might otherwise wish to effect such sales.

We are also registering for resale by certain selling stockholders 919,132 Note Shares, 8,053,565 Conversion Shares, and 440,583 Subject Warrant Shares under this prospectus. In addition, shares of our common stock issuable upon exercise or vesting of incentive awards under our incentive plans are, once issued, eligible for sale in the public market, subject to any lock-up agreements and, in some cases, limitations on volume and manner of sale applicable to affiliates under Rule 144. Furthermore, shares of our common stock reserved for future issuance under our incentive plan may become available for sale in the future.

The market price of shares of our common stock could drop significantly if the holders described above sell or are perceived by the market as intending to sell. These factors could also make it more difficult for us to raise additional funds through future offerings of shares of our common stock or other securities.

We may use proceeds from sales of our common stock made pursuant to the ELOC Purchase Agreement, the conversion of the Preferred Shares or Subject Notes, and the exercise of the Subject Warrants, in ways with which you may not agree or in ways which may not yield a significant return.

We will have broad discretion over the use of proceeds we may receive with respect to our ELOC, the Preferred Shares, the Subject Notes, and the Subject Warrants, and you will not have the opportunity, as part of your investment decision, to assess whether the proceeds are being used appropriately. Because of the number and variability of factors that will determine our use of the net proceeds, their ultimate use may vary substantially from their currently intended use. While we expect to use the net proceeds from this offering as set forth in “Use of Proceeds,” we are not obligated to do so. The failure by us to apply these funds effectively could harm our business, and the net proceeds may be used for corporate purposes that do not increase our operating results or enhance the value of our common stock.

Risks Related to the ELOC

It is not possible to predict the actual number of shares of our common stock, if any, we will sell under the ELOC Purchase Agreement, or the actual gross proceeds resulting from those sales or the dilution to you from those sales. Further, we may not have access to the full amount available under the ELOC Purchase Agreement.

Pursuant to the ELOC Purchase Agreement, Seven Knots shall purchase from us up to $35.0 million of shares of common stock, upon the terms and subject to the conditions and limitations set forth in the ELOC Purchase Agreement (the “Commitment Amount”). We have already sold $11.2 million of ELOC Shares to Seven Knots pursuant to the ELOC Purchase Agreement and may elect, at our sole discretion, to sell from time to time an additional $23.8 million of ELOC Shares to Seven Knots pursuant to the ELOC Purchase Agreement, which may result in the issuance of up to 21,834,103 ELOC Shares based on the average of the high and low reported prices of our common stock as reported on The Nasdaq Capital Market on April 17, 2025, of $1.149 less a 5.0% discount. We are hereby registering all of the foregoing ELOC Shares for resale.

The shares of our common stock that may be issued under the ELOC Purchase Agreement may be sold by us to Seven Knots at our discretion from time to time from the Commencement Date (as defined below) until the earliest to occur of (i) the first day of the month next following the 24-month anniversary of the Commencement Date, (ii) the date on which Seven Knots shall have purchased the Commitment Amount, (iii) the date on which our common stock fails to be listed or quoted on Nasdaq or any Eligible Market (as defined in the ELOC Purchase Agreement), (iv) the thirtieth trading day next following the date on which, pursuant to or within the meaning of any bankruptcy law, we commence a voluntary case or any person commences a proceeding against us, in each case that is not discharged or dismissed prior to such thirtieth trading day, and (v) the date on which, pursuant to or within the meaning of any bankruptcy law, a custodian is appointed for us or for all or substantially all of our property, or we make a general assignment for the benefit of our creditors or each, a Termination Event.

Over the 36-month period from and after the Commencement Date, we will generally have the right to control the timing and amount of any sales of our common stock to Seven Knots when all of the conditions to our right to commence sales are satisfied under the ELOC Purchase Agreement. We may direct Seven Knots to purchase a specified number of shares of common stock on any business day on which the closing sale price of the common stock is equal to or greater than $0.50 (the “Put Threshold”). Though our current market price is greater than the Put Threshold, our stock price may drop below the Put Threshold, and in such instance we may not be able to utilize our ELOC for so long as the Put Threshold remains higher than the market price of our common stock. The last reported sale price of our common stock on The Nasdaq Capital Market on April 24, 2025 was $1.17 per share. Sales of our common stock, if any, to Seven Knots under the ELOC Purchase Agreement will also depend upon market conditions and other factors to be determined by us. We may ultimately decide to sell to Seven Knots all or only a portion of the common stock that may be available for us to sell to Seven Knots pursuant to the ELOC Purchase Agreement. Accordingly, we cannot guarantee that we will be able to sell all of the Commitment Amount or how much in proceeds we may obtain under the ELOC Purchase Agreement. If we cannot sell securities under the ELOC, we may be required to utilize more costly and time-consuming means of accessing the capital markets, which could have a material adverse effect on our liquidity and cash position.

Because the purchase price per share of common stock to be paid by Seven Knots for the ELOC Shares that we may elect to sell to Seven Knots under the ELOC Purchase Agreement, if any, will fluctuate based on the market prices of our common stock at the time we make such election, it is not possible for us to predict, as of the date of this prospectus and prior to any such sales, the number of shares of common stock that we will sell to Seven Knots under the ELOC Purchase Agreement, the purchase price per share that Seven Knots will pay for ELOC Shares purchased from us under the ELOC Purchase Agreement, or the aggregate gross proceeds that we will receive from those purchases by Seven Knots under the ELOC Purchase Agreement.

We are registering $23.8 million of ELOC Shares that we may elect to sell to Seven Knots pursuant to the ELOC Purchase Agreement, which may result in the issuance of up to 21,834,103 ELOC Shares based on the average of the high and low reported prices of our common stock as reported on The Nasdaq Capital Market on April 17, 2025, of $1.149 less a 5.0% discount, under this prospectus. As of April 24, 2025, there were 3,652,317 shares of our common stock outstanding. If all of such 21,834,103 ELOC Shares being registered under this prospectus were issued and outstanding as that date, such shares would represent approximately 85.7% of the total number of shares of our common stock outstanding.

Seven Knots is not obligated to buy any ELOC Shares under the ELOC Purchase Agreement if such shares, when aggregated with all other common stock then beneficially owned by Seven Knots and its affiliates (as calculated pursuant to Section 13(d) of the Securities Exchange Act, and Rule 13d-3 promulgated thereunder), would result in Seven Knots beneficially owning common stock in excess of 4.99% of the then-outstanding shares of common stock. Our inability to access a portion or the full amount available under the ELOC Purchase Agreement, in the absence of any other financing sources, could have a material adverse effect on our business or results of operation.

Seven Knots will pay less than the then-prevailing market price for our common stock, which could cause the price of our common stock to decline.

The purchase price of our common stock to be sold to Seven Knots under the ELOC Purchase Agreement is derived from the market price of our common stock on The Nasdaq Capital Market. Shares to be sold to Seven Knots pursuant to the ELOC Purchase Agreement will be purchased at a discounted price.

For example, we may effect sales to Seven Knots pursuant to a Fixed Purchase Notice at a purchase price equal to the lesser of 95% of (i) the daily volume weighted average price of the common stock for the five trading days immediately preceding the applicable Fixed Purchase Date and (ii) the lowest trading price of a share of common stock during the full trading day on the trading day immediately following the applicable Fixed Purchase Date.

As a result of this pricing structure, Seven Knots’ selling the shares they receive immediately after receipt of such shares could cause the price of our common stock to decrease.

Investors who buy shares of common stock from Seven Knots at different times will likely pay different prices.

Pursuant to the ELOC Purchase Agreement, we have discretion, to vary the timing, price and number of shares of common stock we sell to Seven Knots. If and when we elect to sell shares of common stock to Seven Knots pursuant to the ELOC Purchase Agreement, after Seven Knots has acquired such shares, Seven Knots may resell all, some or none of such shares at any time or from time to time in its sole discretion and at different prices. As a result, investors who purchase shares from Seven Knots in this offering at different times will likely pay different prices for those shares, and so may experience different levels of dilution and in some cases substantial dilution and different outcomes in their investment results. Investors may experience a decline in the value of the shares they purchase from Seven Knots in this offering as a result of future sales made by us to Seven Knots at prices lower than the prices such investors paid for their shares in this offering. In addition, if we sell a substantial number of shares to Seven Knots under the ELOC Purchase Agreement, or if investors expect that we will do so, the actual sales of shares or the mere existence of our arrangements with Seven Knots may make it more difficult for us to sell equity or equity-related securities in the future at a time and at a price that we might otherwise wish to effect such sales.

SPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTS

This prospectus contains “forward-looking statements” within the meaning of Section 27A of the Securities Act of 1933, as amended, or the Securities Act, and Section 21E of the Exchange. These forward-looking statements provide our current expectations or forecasts of future events and financial performance and may be identified by the use of forward-looking terminology, including such terms as “anticipates,” “believes,” “contemplates,” “continues” “could,” “estimates,” “expects,” “intends,” “may,” “plans,” “potential” “predicts,” “projects,” “should,” “targets,” or “will” or, in each case, their negative, or other variations or comparable terminology, though the absence of these words does not necessarily mean that a statement is not forward-looking.

We intend that all forward-looking statements be subject to the safe-harbor provisions of the Private Securities Litigation Reform Act of 1995. Forward-looking statements are subject to many risks and uncertainties that could cause actual results to differ materially from any future results expressed or implied by the forward-looking statements. We caution you therefore against relying on any of these forward-looking statements. They are neither statements of historical fact nor guarantees or assurances of future performance. Examples of such risks and uncertainties, which potentially could have a material adverse effect on our development programs, business and/or operations, include, but are not limited to the following:

Pharmaceutical, biotechnology, and medical technology companies have suffered significant setbacks conducting clinical trials, even after obtaining promising earlier preclinical and clinical data. In addition, data obtained from clinical trials are susceptible to varying interpretations, which could delay, limit or prevent regulatory approval. After gaining approval of a drug product, pharmaceutical and biotechnology companies face considerable challenges in marketing and distributing their products and may never become profitable.

We have based these forward-looking statements largely on our current expectations, estimates, forecasts, and projections about future events and financial trends that we believe may affect our financial condition, results of operations, business strategy, and financial needs. In light of the significant uncertainties in these forward-looking statements, you should not rely upon forward-looking statements as predictions of future events. Although we believe that we have a reasonable basis for each forward-looking statement contained in this prospectus, we cannot guarantee that the future results, levels of activity, performance, or events and circumstances reflected in the forward-looking statements will be achieved or occur at all. You should refer to the section entitled “Risk Factors” in this prospectus and the risk factors set forth in the documents incorporated by reference in this prospectus for a discussion of important factors that may cause our actual results to differ materially from those expressed or implied by our forward-looking statements. Furthermore, if our forward-looking statements prove to be inaccurate, the inaccuracy may be material.

You should read this prospectus, the documents incorporated by reference in this prospectus, any free writing prospectus, and the exhibits included in the registration statement of which this prospectus is a part completely and with the understanding that our actual future results, performance, or achievements may be materially different from what we expect. We qualify all of the forward-looking statements in this prospectus by these cautionary statements.

Trademark Notice

AEROSURF®, AFECTAIR®, SURFAXIN®, SURFAXIN LS™, WINDTREE THERAPEUTICS® (logo), WINDTREE THERAPEUTICS™, and WINDTREE™ are registered and common law trademarks of Windtree Therapeutics, Inc. (Warrington, PA).

THE COMMITTED EQUITY FINANCING

Overview

In July 2024, we entered into the ELOC Purchase Agreement with Seven Knots. Sales of our common stock to Seven Knots under the ELOC Purchase Agreement, and the timing of any sales, will be determined by us from time to time in our sole discretion and will depend on a variety of factors, including, among other things, market conditions, the trading price of our common stock and determinations by us regarding the use of proceeds from any sale of such common stock. The net proceeds from any future sales under the ELOC Purchase Agreement will depend on the frequency with, and prices at, which the common stock are sold to Seven Knots. To the extent we sell shares under the ELOC Purchase Agreement, we currently plan to use the net proceeds for working capital and other general corporate purposes. We cannot predict whether the net proceeds invested will yield a favorable return.

In accordance with our obligations under the ELOC Purchase Agreement and the ELOC Registration Rights Agreement, dated as of June 26, 2024, between us and Seven Knots, pursuant to which we agreed to provide Seven Knots with customary registration rights related to the shares issued under the ELOC Purchase Agreement, we have filed a registration statement of which this prospectus forms a part in order to register the resale of up to 21,834,103 shares that we may elect, in our sole discretion, to issue and sell to Seven Knots, from time to time from and after the Commencement Date upon the terms and subject to the conditions and limitations of the ELOC Purchase Agreement, subject to applicable stock exchange rules.

Seven Knots is not obligated to buy any common stock under the ELOC Purchase Agreement if such shares, when aggregated with all other common stock then beneficially owned by Seven Knots and its respective affiliates (as calculated pursuant to Section 13(d) of the Exchange Act and Rule 13d-3 promulgated thereunder), would result in Seven Knots beneficially owning common stock in excess of 4.99% of the then-outstanding shares of common stock (the “Beneficial Ownership Limitation”).

The ELOC Purchase Agreement and ELOC Registration Rights Agreement contain customary registration rights, representations, warranties, conditions and indemnification obligations by each party. The representations, warranties and covenants contained in such agreements were made only for purposes of such agreements and as of specific dates, were solely for the benefit of the parties to such agreements and are subject to certain important limitations.

ELOC Purchase Agreement

Pursuant to the ELOC Purchase Agreement, Seven Knots shall purchase from us up to $35.0 million of shares of our common stock, upon the terms and subject to the conditions and limitations set forth in the Purchase Agreement (the “Commitment Amount”). Prior to the date of this prospectus, we have issued 342,900 shares of our common stock for total gross cash proceeds of $11.2 million pursuant to the ELOC Purchase Agreement. We are registering $23.8 million of ELOC Shares that we may elect to sell to Seven Knots pursuant to the ELOC Purchase Agreement, which may result in the issuance of up to 21,834,103 ELOC Shares based on the average of the high and low reported prices of our common stock as reported on The Nasdaq Capital Market on April 17, 2025, of $1.149 less a 5.0% discount, under this prospectus. The shares of our common stock that may be issued under the ELOC Purchase Agreement may be sold by us to Seven Knots at our discretion from time to time from the Commencement Date until the earliest to occur of (i) the first day of the month following the 24-month anniversary of the Commencement Date, (ii) the date on which Seven Knots shall have purchased the Commitment Amount, (iii) the date on which our common stock fails to be listed or quoted on The Nasdaq Capital Market or any Eligible Market (as defined in the ELOC Purchase Agreement), (iv) the thirtieth trading day following the date on which, pursuant to or within the meaning of any bankruptcy law, we commence a voluntary case or any person commences a proceeding against us, in each case that is not discharged or dismissed prior to such thirtieth trading day, and (v) the date on which, pursuant to or within the meaning of any bankruptcy law, a custodian is appointed for us or for all or substantially all of our property, or we make a general assignment for the benefit of our creditors.

Purchases of Shares of our Common Stock Under the ELOC Purchase Agreement

During the term described above, on any business day on which the closing sale price of the common stock is equal to or greater than $0.50, we will have the right, but not the obligation, from time to time at our sole discretion, to direct Seven Knots, by delivery of an irrevocable written notice, or a Fixed Purchase Notice, to purchase a number of shares of our common stock, or the Fixed Purchase, up to the lesser of 10,000 shares of common stock or $50,000, or the Fixed Purchase Maximum Amount, at a purchase price equal to the lesser of 95% of (i) the daily VWAP (as defined below) of the common stock for the five trading days immediately preceding the applicable Fixed Purchase Date and (ii) the lowest trading price of a share of common stock during the full trading day on the trading day immediately following the applicable Fixed Purchase Date, or the Fixed Purchase Price provided, however, that if the resulting Fixed Purchase Price is less than $0.50 (to be appropriately adjusted for any reorganization, recapitalization, non-cash dividend, stock split, reverse stock split or other similar transaction), then the percentage applied shall be ninety percent (90%) instead of the ninety-five percent (95%) referred to above.

In addition, at any time from and after the Commencement Date, on any business day on which the closing sale price of the common stock is equal to or greater than $0.50 and such business day is also the Fixed Purchase Date for a Fixed Purchase of an amount of shares of common stock not less than the applicable Fixed Purchase Maximum Amount, we may also direct Seven Knots, by delivery of an irrevocable written notice, or a VWAP Purchase Notice, to purchase, on the immediately following business day, or the VWAP Purchase Date, an additional number of shares of common stock in an amount equal to the lesser of (i) 300% of the number of shares of common stock directed by us to be purchased by Seven Knots for the applicable Fixed Purchase and (ii) 30% of the trading volume in our common stock on Nasdaq during the applicable VWAP Purchase Period (as defined in the Purchase Agreement) on the applicable VWAP Purchase Date, or the VWAP Purchase, at a purchase price equal to the lesser of 90% of (i) the closing sale price of the common stock on the applicable VWAP Purchase Date and (ii) the VWAP during the applicable VWAP Purchase Period, or the VWAP Purchase Price.

At any time from and after the Commencement Date, on any business day that is also the VWAP Purchase Date for a VWAP Purchase, we may also direct Seven Knots, by delivery of an irrevocable written notice, or an Additional VWAP Purchase Notice and, together with a Fixed Purchase Notice and a VWAP Purchase Notice, a Purchase Notice, to purchase, on the same business day, or the Additional VWAP Purchase Date and, together with a Fixed Purchase Date and a VWAP Purchase Date, the Purchase Dates, an additional number of shares of common stock in an amount equal to the lesser of (i) 300% of the number of shares of common stock directed by us to be purchased by Seven Knots for the applicable Fixed Purchase and (ii) 30% of the trading volume in our common stock on Nasdaq during the applicable Additional VWAP Purchase Period (as defined in the Purchase Agreement) on the applicable VWAP Purchase Date, or an Additional VWAP Purchase, and together with a Fixed Purchase and a VWAP Purchase, the Purchases, at a purchase price equal to the lesser of 90% of (i) the closing sale price of the common stock on the applicable Additional VWAP Purchase Date and (ii) the VWAP during the Additional VWAP Purchase Period (as defined in the ELOC Purchase Agreement).

For purposes of the ELOC Purchase Agreement, “VWAP” is, for the common stock for a specified period, the dollar volume-weighted average price for the common stock on Nasdaq, for such period, as reported by Bloomberg through its “AQR” function. All such determinations shall be appropriately adjusted for any sales of shares of common stock through block transactions, any reorganization, non-cash dividend, stock split, reverse stock split, stock combination, recapitalization or other similar transaction during such period.

Fees

We previously paid to Seven Knots $25,000 in cash as reimbursement for the reasonable, out-of-pocket expenses incurred by Seven Knots, including the legal fees and disbursements of Seven Knots’ legal counsel, in connection with its due diligence investigation of our company and in connection with the preparation, negotiation and execution of the ELOC Purchase Agreement.

Termination of the ELOC Purchase Agreement

Unless earlier terminated as provided in the ELOC Purchase Agreement, the ELOC Purchase Agreement will terminate automatically on the earliest to occur of:

We generally have the right to terminate the ELOC Purchase Agreement at any time after Commencement Date, at no cost or penalty, upon one trading days’ prior written notice to Seven Knots. We and Seven Knots may also terminate the ELOC Purchase Agreement at any time by mutual written consent. Seven Knots also has the right to terminate the ELOC Purchase Agreement upon 10 trading days’ prior written notice to us, but only upon the occurrence of certain customary events as listed in the ELOC Purchase Agreement. No termination of the ELOC Purchase Agreement by us or by Seven Knots will become effective prior to the first trading day immediately following the date on which any pending Purchase has been fully settled in accordance with the terms and conditions of the ELOC Purchase Agreement, and will not affect any of our respective rights and obligations under the ELOC Purchase Agreement with respect to any pending Purchase, and both we and Seven Knots have agreed to complete our respective obligations with respect to any such pending Purchase under the ELOC Purchase Agreement.

Prohibition of “Dilutive Issuances” During Pending Purchases

Subject to certain exceptions, during any Reference Period (as defined in the ELOC Purchase Agreement) with respect to a Purchase, we are limited in our ability to issue any common stock, or any securities convertible into common stock, at an effective price per share of common stock less than the applicable Purchase Price to be sold to Seven Knots in the applicable Purchase to which such Reference Period relates.

No Short-Selling or Hedging

Seven Knots has agreed that neither it nor any entity managed or controlled by it, will engage in, directly or indirectly, any (i) “short sale” (as such term is defined in Rule 200 of Regulation SHO of the Exchange Act) of the common stock or (ii) hedging transaction, which, with respect to items (i) and (ii), establishes a net short position with respect to the common stock, during the term of the applicable ELOC Purchase Agreement.

Effect of Sales of our Common Stock under the ELOC Purchase Agreement on our Stockholders

The common stock issued under the ELOC Purchase Agreement that is being registered for resale in this offering may be issued and sold by us to the Seven Knots from time to time at our discretion, during the terms described above. The resale by Seven Knots of a significant quantity of shares registered for resale in this offering at any given time, or the perception that these sales may occur, could cause the market price of our common stock to decline and to be highly volatile. Additional sales of our common stock, if any, to Seven Knots under the ELOC Purchase Agreement will be determined by us in our sole discretion, subject to the satisfaction of certain conditions in the ELOC Purchase Agreement, and will depend upon market conditions and other factors. We may ultimately decide to sell to Seven Knots all, some or none of the common stock that may be available for us to sell to Seven Knots pursuant to the ELOC Purchase Agreement. If we elect to sell common stock to Seven Knots pursuant to the ELOC Purchase Agreement, after Seven Knots has acquired such shares, Seven Knots may resell all, some or none of such common stock at any time or from time to time in its discretion and at different prices. As a result, investors who purchase common stock from Seven Knots in this offering at different times will likely pay different prices for those shares of common stock, and so may experience different levels of dilution and in some cases substantial dilution and different outcomes in their investment results. See “Risk Factors—Risks Related to the ELOC—Investors who buy shares of common stock from Seven Knots at different times will likely pay different prices.”

Investors may experience a decline in the value of the common stock they purchase from Seven Knots in this offering as a result of future sales made by us to Seven Knots at prices lower than the prices such investors paid for their shares in this offering. In addition, if we sell a substantial number of shares of common stock to Seven Knots under the ELOC Purchase Agreement, or if investors expect that we will do so, the actual sales of common stock or the mere existence of our arrangement with Seven Knots may make it more difficult for us to sell equity or equity-related securities in the future at a time and at a price that we might otherwise wish to effect such sales.

Because the purchase price per share to be paid by Seven Knots for the common stock that we may elect to sell to Seven Knots under the ELOC Purchase Agreement, if any, will fluctuate based on the market prices of our common stock at the time we make such election, as of the date of this prospectus, it is not possible for us to predict the number of shares of common stock that we will sell to Seven Knots under the ELOC Purchase Agreement, the actual purchase price per share to be paid by Seven Knots for those shares of common stock, or the actual gross proceeds to be raised by us from those sales, if any.

We have already sold 342,900 ELOC Shares to Seven Knots pursuant to the ELOC Purchase Agreement and may elect, at our sole discretion, to sell from time to time an additional $23.8 million of ELOC Shares to Seven Knots pursuant to the ELOC Purchase Agreement, which may result in the issuance of up to 21,834,103 ELOC Shares based on the average of the high and low reported prices of our common stock as reported on The Nasdaq Capital Market on April 17, 2025, of $1.149 less a 5.0% discount. As of April 24, 2025, there were 3,652,317 shares of common stock outstanding. If all of the 21,834,103 ELOC Shares being registered under this prospectus were issued and outstanding as of April 17, 2025, such shares would represent approximately 85.7% of total number of shares of our common stock outstanding. The actual number of shares of our common stock issuable will vary depending on the then current market price of shares of our common stock sold to Seven Knots in this offering.

The number of shares of common stock ultimately offered for sale by Seven Knots for resale under this prospectus is dependent upon the number of shares of common stock, if any, we ultimately sell to Seven Knots under the ELOC Purchase Agreement. Further, if and when we elect to sell shares of common stock to Seven Knots pursuant to the ELOC Purchase Agreement, after Seven Knots has acquired such shares, Seven Knots may resell all, some or none of such shares of common stock at any time or from time to time in its discretion and at different prices.

The issuance of our shares of common stock to Seven Knots pursuant to the ELOC Purchase Agreement will not affect the rights or privileges of our existing stockholders, except that the economic and voting interests of each of our existing stockholders will be diluted. Although the number of shares of common stock that our existing stockholders own will not decrease, the shares of common stock owned by our existing stockholders will represent a smaller percentage of our total outstanding shares of common stock after any such issuance.

The following table sets forth the number of ELOC Shares that we have issued and may issue from time to time to Seven Knots under the ELOC Purchase Agreement registered hereunder at varying purchase prices:

USE OF PROCEEDS

All of the shares of common stock offered by the selling stockholders pursuant to this prospectus will be sold by the selling stockholders for their respective accounts. We will not receive any of the proceeds from the sale or other disposition by the selling stockholders of the shares of common stock. However, we may receive (i) up to approximately $0.2 million from the exercise of the Subject Warrants for cash and (ii) up to $23.8 million from sales of ELOC Shares to Seven Knots. We intend to use the foregoing proceeds, if any, for working capital and general corporate purposes.

The selling stockholders will pay any underwriting discounts and commissions and expenses incurred by the selling stockholders for brokerage, accounting, tax or legal services or any other expenses incurred by the selling stockholders in disposing of the shares of common stock being registered hereby.

We are paying the cost of registering the shares of common stock covered by this prospectus as well as various related expenses, including, without limitation, all registration and filing fees, Nasdaq listing fees and fees and expenses of our counsel and our accountants.

DIVIDEND POLICY

We have not paid any cash dividends on our common stock and we do not anticipate paying any cash dividends on our common stock in the foreseeable future and we intend to retain all of our earnings, if any, to finance our growth and operations and to fund the expansion of our business. However, holders of our Series C Convertible Preferred Stock, par value $0.001 per share (the “Series C Preferred Stock”), are entitled to receive dividends payable quarterly in arrears, at a rate of 10.0% per annum of the stated value of $1,000 per share. Dividends began accruing on, and are cumulative from, July 19, 2024, and are payable in the form of common stock based on a per share price equal to $1.10 as of April 24, 2025, subject to adjustment as provided in the Certificate of Designations. Dividends are also payable upon any redemption in accordance with the Certificate of Designations or upon any required payment upon any Bankruptcy Triggering Event (as defined in the Certificate of Designations). From and after the occurrence and during the continuance of any Triggering Event (as defined in the Certificate of Designations), the dividend rate automatically increases to 18.0% per annum.

SELLING STOCKHOLDERS

This prospectus relates to the possible resale from time to time by the selling stockholder of (i) an aggregate of 8,053,565 Conversion Shares, (ii) an aggregate of 440,583 Subject Warrant Shares, (iii) an aggregate of 919,132 Note Shares, and (iv) an aggregate of 21,834,103 ELOC Shares. We are registering the shares of common stock in order to permit the selling stockholders to offer the shares for resale from time to time.

The term “selling stockholders” includes the stockholders listed below and their transferees, pledges, donees or other successors-in-interest who may acquire shares from a selling stockholder as a gift, pledge, partnership distribution or other non-sale related transfer after the date of this prospectus. Information concerning the selling stockholders may change after the date of this prospectus and changed information will be presented in a supplement to this prospectus if and when required.

For additional information regarding the issuance of common stock covered by this prospectus, see the sections entitled “The Committed Equity Financing” and “Prospectus Summary—Background of Related Transactions” above. Except as described above in the sections of this prospectus entitled “The Committed Equity Financing” and “Prospectus Summary—Background of Related Transactions” and as described below in “—Material Relationship Between the Selling Stockholders and Windtree,” the selling stockholders has not had any material relationship with us within the past three years.

The table below presents information regarding the selling stockholders and the shares of common stock that it may offer from time to time under this prospectus. This table is prepared based on information supplied to us by the selling stockholders, and reflects holdings as of April 24, 2025. The number of shares in the column “Maximum Number of Shares of Common Stock to be Offered Pursuant to this Prospectus” represents all of the shares of common stock that the selling stockholders may offer under this prospectus. The selling stockholders may sell some, all or none of its shares in this offering. We do not know how long the selling stockholders will hold the shares before selling them, and we currently have no agreements, arrangements or understandings with the selling stockholders regarding the sale of any of the shares.

Beneficial ownership is determined in accordance with Rule 13d-3(d) promulgated by the SEC under the Exchange Act, and includes shares of common stock with respect to which the selling stockholder have voting and investment power. The percentage of common stock beneficially owned by the selling stockholder prior to the offering shown in the table below is based on an aggregate of 3,652,317 shares of our common stock outstanding on April 24, 2025. The fourth column assumes the sale of all of the shares offered by the selling stockholders pursuant to this prospectus.

Through the date of this prospectus, we have sold 342,900 ELOC Shares to Seven Knots pursuant to the ELOC Purchase Agreement and may elect, at our sole discretion, to sell from time to time an additional $23.8 million of ELOC Shares to Seven Knots pursuant to the ELOC Purchase Agreement, which may result in the issuance of up to 21,834,103 ELOC Shares based on the average of the high and low reported prices of our common stock as reported on The Nasdaq Capital Market on April 17, 2025, of $1.149 less a 5.0% discount. Because the purchase price of the common stock issuable under the ELOC Purchase Agreement is determined on each Fixed Purchase Date, with respect to a Fixed Purchase, on the applicable VWAP Purchase Date, with respect to a VWAP Purchase, and on the applicable Additional VWAP Purchase Date, with respect to an Additional VWAP Purchase, the aggregate number of shares that may actually be sold by us to Seven Knots under the ELOC Purchase Agreement may be fewer than the number of shares being offered by this prospectus.

In accordance with the terms of a registration rights agreement with the holders of the Preferred Shares and the Subject Warrants, this prospectus generally includes the resale of 300% of the sum of (i) the maximum number of shares of common stock issuable pursuant to the Series C Certificate of Designations, including payment of dividends on the Preferred Shares through the maturity date of January 19, 2026, and (ii) the maximum number of shares of common stock issuable upon exercise of the Subject Warrants, in each case, determined as if the outstanding Preferred Shares (including payment of 10% dividends on the Preferred Shares through the maturity date of January 19, 2026) and the Subject Warrants were converted or exercised (as the case may be) in full (without regard to any limitations on conversion or exercise contained therein solely for the purpose of such calculation) at a conversion price or exercise price (as the case may be) calculated as of the trading day immediately preceding the date this registration statement was initially filed with the SEC. Because the conversion price of the Preferred Shares and the exercise price of the Subject Warrants may be adjusted, the number of shares that will actually be issued may be more or less than the number of shares being offered by this prospectus.

Under the terms of the Preferred Shares and the Subject Warrants, a selling stockholder may not convert the Preferred Shares or exercise the Subject Warrants to the extent (but only to the extent) such selling stockholder or any of its affiliates would beneficially own a number of shares of our common stock which would exceed 4.99% of our outstanding shares. The number of shares in the second column reflects these limitations. The selling stockholders may sell all, some or none of their shares in this offering. See “Plan of Distribution.”

In accordance with the terms of the Subject Notes, we are registering 300% of the maximum aggregate number of shares of common stock issuable upon conversion in full of the Subject Notes, including accrued interest through the maturity date of each Subject Note.

We may amend or supplement this prospectus from time to time in the future to update or change the selling stockholder list and the securities that may be resold.

Please see the section titled “Plan of Distribution” for further information regarding the selling stockholders’ method of distributing these securities.

Material Relationship Between the Selling Stockholders and Windtree

Seven Knots

On June 26, 2024, we entered into the ELOC Purchase Agreement with Seven Knots, as an equity line investor, whereby we have the right, but not the obligation, to sell to Seven Knots, and Seven Knots is obligated to purchase from us up to $23.8 million of newly issued shares of common stock. We will control the timing and amount of any sales of common stock to Seven Knots. Actual sales of shares of our common stock to Seven Knots under the ELOC Purchase Agreement will depend on a variety of factors to be determined by us from time to time, including, among others, market conditions, the trading price of our common stock and determinations by us as to the appropriate sources of funding and our operations. Seven Knots also purchased a Subject Note in an initial principal amount of $156,250. We are also registering the shares of common stock issuable upon conversion of the Subject Note held by Seven Knots.

Craig Fraser

Mr. Fraser served as our President and Chief Executive Officer and a member of our board of directors since February 2016. He served as our Chairman from June 2023 to December 2024. Mr. Fraser resigned from the board of directors on April 17, 2025.

Steven Simonson, M.D.

Dr. Simonson has served as our Senior Vice President and Chief Medical Officer since April 2017.

Ladenburg Thalmann & Co. Inc.

In January 2023, we engaged Ladenburg Thalmann & Co. Inc. (“Ladenburg”), as our exclusive placement agent in connection with warrant exercise inducement offer letters with certain holders of (i) our warrants issued in December 2019, (ii) our warrants issued in May 2020 and (iii) our warrants issued in March 2021. We agreed to pay Ladenburg a fee equal to 8% of its gross proceeds from the exercise of such warrants. We also agreed to pay Ladenburg a management fee equal to 1% of the gross proceeds from the exercise of such warrants.

In February 2023, we engaged Ladenburg as our exclusive placement agent in connection with warrant exercise inducement offer letters with certain holders of (i) our warrants issued in July 2018, (ii) our warrants issued in December 2018, (iii) our warrants issued in December 2019 and (iv) our warrants issued in May 2020. We agreed to pay Ladenburg a fee equal to 8% of its gross proceeds from the exercise of such warrants. We also agreed to pay Ladenburg a management fee equal to 1% of the gross proceeds from the exercise of such warrants.

In April 2023, we entered into an underwriting agreement with Ladenburg as the sole underwriter, relating to the issuance and sale in a public offering of 204,779 shares of our common stock, and accompanying warrants exercisable for an aggregate of 204,779 shares of common stock. The public offering closed on April 24, 2023, which included Ladenburg’s exercise in full of its option to purchase an additional 30,717 shares of common stock and warrants to purchase up to an additional 30,717 shares of common stock.

On November 9, 2023, we entered into an At The Market Program (the “2023 ATM Program”) with Ladenburg, as agent. We are not obligated to make any sales under the 2023 ATM Program. When we issue sale notices to Ladenburg, we designate the maximum amount of shares to be sold by Ladenburg daily and the minimum price per share at which shares may be sold. Ladenburg may sell shares by any method permitted by law deemed to be an “at-the-market offering” as defined in Rule 415(a)(4) under the Securities Act of 1933, as amended, or in privately negotiated transactions.

DESCRIPTION OF SECURITIES

The following description of our capital stock is not complete and may not contain all the information you should consider before investing in our capital stock. This description is summarized from, and qualified in its entirety by reference to our Amended and Restated Certificate of Incorporation, which has been publicly filed with the SEC. See “Where You Can Find More Information” and “Incorporation of Certain Information by Reference.”

Capital Stock

Our authorized capital stock consists of 120,000,000 shares of common stock, par value $0.001 per share and 5,000,000 shares of preferred stock, par value $0.001 per share.

Common Stock

Voting Rights

Each holder of common stock is entitled to one vote for each share on all matters submitted to a vote of the stockholders, including the election of directors. Our stockholders do not have cumulative voting rights in the election of directors. The affirmative vote of the voting power of the outstanding shares of capital stock entitled to vote, voting as a single class, will be required to amend certain provisions of our Amended and Restated Certificate of Incorporation (as amended, the “Charter”), including the provisions relating to amending our By-Laws, procedures for our stockholder meetings, director liability, and exclusive forum for proceedings.

Dividends

Subject to preferences that may be applicable to any then outstanding preferred stock, holders of our common stock are entitled to receive dividends, if any, as may be declared from time to time by our board of directors out of legally available funds.

Liquidation

In the event of our liquidation, dissolution or winding up, holders of our common stock will be entitled to share ratably in the net assets legally available for distribution to stockholders after the payment of all of our debts and other liabilities, subject to the satisfaction of any liquidation preference granted to the holders of any then outstanding shares of preferred stock.

Rights and Preferences

Holders of our common stock have no preemptive, conversion or subscription rights, and there are no redemption or sinking fund provisions applicable to our common stock. In the event of a liquidation, dissolution or winding up of us, holders of our common stock will be entitled to share ratably in all assets remaining after payment of all debts and other liabilities and any liquidation preference of any outstanding preferred stock.

Number of Holders

There are approximately 26 holders of our common stock as of April 15, 2025.

Reverse Stock Splits

On April 28, 2020, we filed an amendment to our Charter in order to effect a 1-for-3 reverse stock split of our common stock effective for trading purposes on May 29, 2020. The number of authorized stock remained unchanged at 120,000,000 shares.

On February 22, 2023, we filed an amendment to our Charter in order to effect a 1-for-50 reverse stock split of our common stock effective for trading purposes on February 24, 2023. The number of authorized stock remained unchanged at 120,000,000 shares.

On April 19, 2024, we filed an amendment to our Charter in order to effect a 1-for-18 reverse stock split of our common stock effective for trading purposes on April 22, 2024. The number of authorized stock remained unchanged at 120,000,000 shares.

On February 14, 2025, we filed an amendment to our Charter in order to effect a 1-for-50 reverse stock split of our common stock effective for trading purposes on February 21, 2025. The number of authorized stock remained unchanged at 120,000,000 shares.

Preferred Stock

Our board of directors currently has the authority, without further action by our stockholders, to issue up to 5,000,000 shares of preferred stock in one or more series and to fix the rights, preferences, privileges and restrictions thereof. These rights, preferences and privileges could include dividend rights, conversion rights, voting rights, terms of redemption, liquidation preferences, sinking fund terms and the number of shares constituting, or the designation of, such series, any or all of which may be greater than the rights of common stock. The issuance of preferred stock by us could adversely affect the voting power of holders of our common stock and the likelihood that such holders will receive dividend payments and payments upon a liquidation of us. In addition, the issuance of preferred stock could have the effect of delaying, deferring or preventing a change in control of us or other corporate action.

Of the 5,000,000 authorized shares of preferred stock, 40,000 shares are designated as Series A Preferred Stock, 5,500 shares are designated as Series B Convertible Preferred Stock and 18,820 shares are designated as Series C Preferred Stock. As of April 24, 2025, there are no shares of Series A Preferred Stock outstanding, no shares of Series B Convertible Preferred Stock outstanding, and 2,727 shares of Series C Preferred Stock outstanding. We have no present plans to issue any additional shares of preferred stock.

Anti-Takeover Provisions

Certificate of Incorporation and By-Laws

Among other things, our Amended and Restated Certificate of Incorporation (as amended, the “Certificate of Incorporation”) and Amended and Restated By-Laws (as amended, the “By-Laws”):

The amendment of any of these provisions would require the affirmative vote of the majority of voting power of the outstanding shares of capital stock entitled to vote.

The combination of these provisions makes it more difficult for our stockholders to replace our board of directors as well as for another party to obtain control of us by replacing our board of directors. Because our board of directors has the power to retain and discharge our officers, these provisions could also make it more difficult for existing stockholders or another party to effect a change in management. In addition, the authorization of undesignated preferred stock makes it possible for our board of directors to issue preferred stock with voting or other rights or preferences that could impede the success of any attempt to change our control.

These provisions are intended to enhance the likelihood of continued stability in the composition of our board of directors and its policies and to discourage coercive takeover practices and inadequate takeover bids. These provisions are also designed to reduce our vulnerability to hostile takeovers and to discourage certain tactics that may be used in proxy fights. However, such provisions could have the effect of discouraging others from making tender offers for our shares and may have the effect of delaying changes in our control or management. As a consequence, these provisions may also inhibit fluctuations in the market price of our stock that could result from actual or rumored takeover attempts. We believe that the benefits of these provisions, including increased protection of our potential ability to negotiate with the proponent of an unfriendly or unsolicited proposal to acquire or restructure our Company, outweigh the disadvantages of discouraging takeover proposals, because negotiation of takeover proposals could result in an improvement of their terms.

Section 203 of the Delaware General Corporation Law

We are subject to Section 203 of the Delaware General Corporation Law (the “DGCL”), which prohibits a Delaware corporation from engaging in any business combination with any interested stockholder for a period of three years after the date that such stockholder became an interested stockholder, with the following exceptions:

In general, Section 203 defines a “business combination” to include the following:

In general, Section 203 defines an “interested stockholder” as an entity or person who, together with the person’s affiliates and associates, beneficially owns, or within three years prior to the time of determination of interested stockholder status did own, 15% or more of the outstanding voting stock of the corporation.

The statute could prohibit or delay mergers or other takeover or change in control attempts and, accordingly, may discourage attempts to acquire us even though such a transaction may offer our stockholders the opportunity to sell their stock at a price above the prevailing market price.

A Delaware corporation may “opt out” of these provisions with an express provision in its certificate of incorporation. We have not opted out of these provisions, which may as a result, discourage or prevent mergers or other takeover or change of control attempts of us.

Choice of Forum

Our Certificate of Incorporation provides that the Court of Chancery of the State of Delaware shall be the sole and exclusive forum for the following claims or causes of action brought under Delaware statutory or common law: (1) any derivative claim or action brought on our behalf; (2) any claim or cause of action asserting a breach of fiduciary duty by any of our directors or officers; (3) any claim or cause of action asserting a claim against us arising out of, or pursuant to, the DGCL, our Certificate of Incorporation or our By-Laws; or (4) any action asserting a claim against the Company governed by the internal affairs doctrine.

Limitations of Liability and Indemnification

Our Certificate of Incorporation and our By-Laws limit our directors’ liability and may indemnify our directors and officers to the fullest extent permitted under the DGCL. The DGCL provides that directors of a corporation will not be personally liable for monetary damages for breach of their fiduciary duties as directors, except for liability for:

The DGCL and our By-Laws provide that we will, in certain situations, indemnify our directors and officers, to the fullest extent permitted by law.

We have entered into indemnification agreements with our directors and officers. These indemnification agreements may require us, among other things, to indemnify our directors and officers for some expenses, including attorneys’ fees, judgments, penalties, fines and settlement amounts incurred by a director or officer in any action or proceeding arising out of his or her service as one of our directors or officers, or any of our subsidiaries or any other company or enterprise to which the person provides services at our request. Subject to certain limitations, our indemnification agreements also require us to advance expenses incurred by our directors and officers for the defense of any action for which indemnification is required or permitted.

We maintain a directors’ and officers’ insurance policy pursuant to which our directors and officers are insured against liability for actions taken in their capacities as directors and officers. We believe that these provisions in our Certificate of Incorporation, our By-Laws and these indemnification agreements are necessary to attract and retain qualified persons as directors and officers.

The limitation of liability and indemnification provisions in our Certificate of Incorporation and By-Laws may discourage stockholders from bringing a lawsuit against our directors and officers for breach of their fiduciary duty. They may also reduce the likelihood of derivative litigation against our directors and officers, even though an action, if successful, might benefit us and our stockholders. Further, a stockholder’s investment may be adversely affected to the extent that we pay the costs of settlement and damage awards against directors and officers as required by these indemnification provisions.

At present, there is no material pending litigation or proceeding involving any of our directors, officers or employees for which indemnification is sought and we are not aware of any threatened material litigation that may result in claims for indemnification.

Insofar as indemnification for liabilities arising under the Securities Act of 1933, as amended, may be permitted to directors, officers or control persons, in the opinion of the SEC, such indemnification is against public policy, as expressed in the Securities Act, and is therefore unenforceable.

Listing

Our common stock is listed on The Nasdaq Capital Market under the trading symbol “WINT”.

Transfer Agent and Registrar

The transfer agent and registrar for our common stock is Continental Stock Transfer & Trust Company.

PLAN OF DISTRIBUTION

We are registering the shares of our common stock to permit the resale of the shares of common stock by the holders of certain of our securities from time to time after the date of this prospectus. We will not receive any of the proceeds from the sale by the selling stockholders of the shares of common stock, although we will receive the proceeds from any exercise of the Subject Warrants for cash and sales of ELOC Shares for aggregate gross proceeds of up to $23.8 million under the ELOC Purchase Agreement. We will bear all fees and expenses incident to our obligation to register the shares of common stock.

The selling stockholders may sell all or a portion of the shares of common stock held by them and offered hereby from time to time directly or through one or more underwriters, broker-dealers, or agents. If the shares of common stock are sold through underwriters or broker-dealers, the selling stockholders will be responsible for underwriting discounts or commissions or agent’s commissions. The shares of common stock may be sold in one or more transactions at fixed prices, at prevailing market prices at the time of the sale, at varying prices determined at the time of sale or at negotiated prices. These sales may be effected in transactions, which may involve crosses or block transactions, pursuant to one or more of the following methods:

The selling stockholders may also sell the shares of common stock under Rule 144 promulgated under the Securities Act of 1933, as amended, if available, rather than under this prospectus. In addition, the selling stockholders may transfer the shares of common stock by other means not described in this prospectus. If the selling stockholders effect such transactions by selling the shares of common stock to or through underwriters, broker-dealers or agents, such underwriters, broker-dealers or agents may receive commissions in the form of discounts, concessions or commissions from the selling stockholders or commissions from purchasers of the shares of common stock for whom they may act as agent or to whom they may sell as principal (which discounts, concessions or commissions as to particular underwriters, broker-dealers or agents may be in excess of those customary in the types of transactions involved). In connection with sales of the shares of common stock or otherwise, the selling stockholders may enter into hedging transactions with broker-dealers, which may in turn engage in short sales of the shares of common stock in the course of hedging in positions they assume. The selling stockholders may also sell the shares of common stock short and deliver the shares of common stock covered by this prospectus to close out short positions and to return borrowed shares in connection with such short sales. The selling stockholders may also loan or pledge the shares of common stock to broker-dealers that in turn may sell such shares.

Seven Knots has represented to us that at no time prior to the date of the ELOC Purchase Agreement has Seven Knots or its agents, representatives or affiliates engaged in or effected, in any manner whatsoever, directly or indirectly, any short sale (as such term is defined in Rule 200 of Regulation SHO of the Exchange Act) of our common stock or any hedging transaction, which establishes a net short position with respect to our common stock. Seven Knots has agreed that during the term of the ELOC Purchase Agreement, neither Seven Knots, nor any of its agents, representatives or affiliates will enter into or effect, directly or indirectly, any of the foregoing transactions.

In order to comply with the securities laws of certain states, if applicable, the ELOC Shares may be sold only through registered or licensed brokers or dealers. In addition, in certain states, the shares may not be sold unless they have been registered or qualified for sale in the state or an exemption from the state’s registration or qualification requirement is available and complied with.

Seven Knots is an “underwriter” within the meaning of Section 2(a)(11) of the Securities Act.

The selling stockholders may pledge or grant a security interest in some or all of the Preferred Shares, Subject Warrants, Subject Notes or shares of common stock owned by them and, if they default in the performance of their secured obligations, the pledgees or secured parties may offer and sell the shares of common stock from time to time pursuant to this prospectus or any amendment to this prospectus under Rule 424(b)(3) or other applicable provision of the Securities Act amending, if necessary, the list of selling stockholders to include the pledgee, transferee or other successors in interest as selling stockholders under this prospectus. The selling stockholders also may transfer and donate the shares of common stock in other circumstances in which case the transferees, donees, pledgees or other successors in interest will be the selling beneficial owners for purposes of this prospectus.

To the extent required by the Securities Act and the rules and regulations thereunder, the selling stockholders and any broker-dealer participating in the distribution of the shares of common stock may be deemed to be “underwriters” within the meaning of the Securities Act, and any commission paid, or any discounts or concessions allowed to, any such broker-dealer may be deemed to be underwriting commissions or discounts under the Securities Act. At the time a particular offering of the shares of common stock is made, a prospectus supplement, if required, will be distributed, which will set forth the aggregate amount of shares of common stock being offered and the terms of the offering, including the name or names of any broker-dealers or agents, any discounts, commissions and other terms constituting compensation from the selling stockholders and any discounts, commissions or concessions allowed or re-allowed or paid to broker-dealers.

Under the securities laws of some states, the shares of common stock may be sold in such states only through registered or licensed brokers or dealers. In addition, in some states the shares of common stock may not be sold unless such shares have been registered or qualified for sale in such state or an exemption from registration or qualification is available and is complied with.

There can be no assurance that any selling stockholders will sell any or all of the shares of common stock registered pursuant to the registration statement, of which this prospectus forms a part.

The selling stockholders and any other person participating in such distribution will be subject to applicable provisions of the Exchange Act, and the rules and regulations thereunder, including, without limitation, to the extent applicable, Regulation M of the Exchange Act, which may limit the timing of purchases and sales of any of the shares of common stock by the selling stockholders and any other participating person. To the extent applicable, Regulation M may also restrict the ability of any person engaged in the distribution of the shares of common stock to engage in market-making activities with respect to the shares of common stock. All of the foregoing may affect the marketability of the shares of common stock and the ability of any person or entity to engage in market-making activities with respect to the shares of common stock.

We will pay all expenses of the registration of the shares of common stock pursuant to the registration rights agreement, estimated to be $0.1 million in total, including, without limitation, Securities and Exchange Commission filing fees and expenses of compliance with state securities or “blue sky” laws; provided, however, a selling stockholder will pay all underwriting discounts and selling commissions, if any. We will indemnify the selling stockholders against liabilities, including some liabilities under the Securities Act in accordance with the registration rights agreements or other relevant agreements, or the selling stockholders will be entitled to contribution. We may be indemnified by the selling stockholders against civil liabilities, including liabilities under the Securities Act that may arise from any written information furnished to us by the selling stockholders specifically for use in this prospectus, in accordance with the related registration rights agreements or other relevant agreements, or we may be entitled to contribution. Insofar as indemnification for liabilities arising under the Securities Act may be permitted to our directors, officers, and controlling persons, we have been advised that in the opinion of the SEC this indemnification is against public policy as expressed in the Securities Act and is therefore, unenforceable.

Once sold under the registration statement, of which this prospectus forms a part, the shares of common stock will be freely tradable in the hands of persons other than our affiliates.

As consideration for its irrevocable commitment to purchase our common stock under the ELOC Purchase Agreement, we issued to Seven Knots a convertible promissory note with a $350,000 principal amount in accordance with the Purchase Agreement, which has since been fully exercised. We also previously paid to Seven Knots $25,000 in cash as reimbursement for the reasonable, out-of-pocket expenses incurred by Seven Knots, including the legal fees and disbursements of Seven Knots’ legal counsel, in connection with its due diligence investigation of the Company and in connection with the preparation, negotiation and execution of the ELOC Purchase Agreement. See “The Committed Equity Financing” for more information.

LEGAL MATTERS

The validity of the issuance of the common stock offered by this prospectus will be passed upon for us by Thompson Hine LLP, New York, New York.

EXPERTS

The consolidated balance sheets of Windtree Therapeutics, Inc. and Subsidiaries as of December 31, 2024 and 2023, and the related consolidated statements of operations, changes in mezzanine equity and stockholders’ equity, and cash flows for each of the years then ended have been audited by EisnerAmper LLP, independent registered public accounting firm, as stated in their report, which is incorporated herein by reference, which report includes an explanatory paragraph about the existence of substantial doubt concerning our ability to continue as a going concern. Such financial statements have been incorporated herein by reference in reliance on the report of such firm given upon their authority as experts in accounting and auditing.

WHERE YOU CAN FIND MORE INFORMATION

This prospectus forms part of a registration statement on Form S-1 that we filed with the SEC. This prospectus does not contain all of the information set forth in the registration statement, the exhibits to the registration statement, or the documents incorporated by reference herein and therein. For further information with respect to us and the securities that we are offering under this prospectus, we refer you to the registration statement and the exhibits and schedules filed as a part of the registration statement and the documents incorporated by reference herein and therein. You should rely only on the information contained in this prospectus, the documents incorporated by reference herein, and the exhibits to the registration statement. We have not authorized anyone else to provide you with different information. Where we make statements in this prospectus as to the contents of any contract or any other document, for the complete text of that document, we refer you to the copy of the contract or other document filed as an exhibit to the registration statement. Each of these statements is qualified in all respects by this reference.

We are not making an offer of these securities in any state where the offer is not permitted. You should not assume that the information in this prospectus is accurate as of any date other than the date on the front page of this prospectus, regardless of the time of delivery of this prospectus or any sale of the securities offered hereby. We file annual, quarterly and current reports, proxy statements and other information with the SEC. The SEC maintains a website that contains reports, proxy statements and other information regarding issuers that file electronically with the SEC, including Windtree. The address of the SEC website is www.sec.gov.

We also maintain a website at https://ir.windtreetx.com/filings/sec-filings, at which you may access these materials free of charge as soon as reasonably practicable after they are electronically filed with, or furnished to, the SEC. Information contained on or accessible through our website is not a part of this prospectus, and the inclusion of our website address in this prospectus is an inactive textual reference only.

INCORPORATION OF CERTAIN INFORMATION BY REFERENCE

The SEC allows us to “incorporate by reference” information from other documents that we file with it, which means that we can disclose important information to you by referring you to those documents. The information incorporated by reference is considered to be part of this prospectus. Information in this prospectus supersedes information incorporated by reference that we filed with the SEC prior to the date of this prospectus. We incorporate by reference into this prospectus and the registration statement of which this prospectus is a part the information or documents listed below that we filed with the SEC:

Notwithstanding the statements in the preceding paragraphs, no document, report or exhibit (or portion of any of the foregoing) or any other information that we have “furnished” to the SEC pursuant to the Exchange Act shall be incorporated by reference into this prospectus.

We also incorporate by reference into this prospectus all documents (other than current reports furnished under Item 2.02 or Item 7.01 of Form 8-K and exhibits filed on such form that are related to such items) that are filed by us with the SEC pursuant to Sections 13(a), 13(c), 14, or 15(d) of the Exchange Act subsequent to the date of this prospectus until the termination of the offering. These documents include periodic reports, such as Annual Reports on Form 10-K, Quarterly Reports on Form 10-Q, and Current Reports on Form 8-K, as well as proxy statements on Schedule 14A.

We will provide to each person, including any beneficial owner, to whom a prospectus is delivered, without charge upon written or oral request, a copy of any or all of the documents that are incorporated by reference into this prospectus but not delivered with the prospectus, including exhibits that are specifically incorporated by reference into such documents. You should direct any requests for documents to Windtree Therapeutics, Inc., 2600 Kelly Road, Suite 100, Warrington, Pennsylvania 18976, Attn: Corporate Secretary.

You also may access these filings on our website at https://ir.windtreetx.com/filings/sec-filings. We do not incorporate the information on our website into this prospectus or any supplement to this prospectus and you should not consider any information on, or that can be accessed through, our website as part of this prospectus or any supplement to this prospectus (other than those filings with the SEC that we specifically incorporate by reference into this prospectus or any supplement to this prospectus). You may also access these filings at the SEC’s website at http://www.sec.gov.

Any statement contained in a document incorporated or deemed to be incorporated by reference in this prospectus will be deemed modified, superseded or replaced for purposes of this prospectus to the extent that a statement contained in this prospectus modifies, supersedes or replaces such statement.

Up to 31,247,383 Shares of Common Stock

PROSPECTUS

Neither we nor the selling stockholders authorized any dealer, salesperson, or other person to give you written information other than this prospectus or to make representations as to matters not stated in this prospectus. You must not rely on unauthorized information. This prospectus is not an offer to sell these securities or our solicitation of your offer to buy these securities in any jurisdiction where that would not be permitted or legal. Neither the delivery of this prospectus nor any sales made hereunder after the date of this prospectus shall create an implication that the information contained herein or the affairs of the Company have not changed since the date of this prospectus.

April 25, 2025