UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d) of the

Securities Exchange Act of 1934

Date of report (Date of earliest event reported): October 26, 2023

Mustang Bio, Inc.

(Exact Name of Registrant as Specified in Charter)

377 Plantation Street

Worcester, Massachusetts 01605

(Address of Principal Executive Offices)

(781) 652-4500

(Registrant’s telephone number, including area code)

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

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

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

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

On October 26, 2023, Mustang Bio, Inc. (the “Company”) entered into a Securities Purchase Agreement (the “Purchase Agreement”) with a single institutional accredited investor (the “Investor”) pursuant to which the Company agreed to issue and sell, in a registered direct offering priced at-the-market under the rules of The Nasdaq Stock Market (the “Registered Offering”), (i) 920,000 shares (the “Shares”) of common stock of the Company, $0.0001 par value per share (the “Common Stock”), at a price per Share of $1.70 and (ii) pre-funded warrants (the “Pre-funded Warrants”) to purchase up to 1,668,236 shares of Common Stock, at a price per Pre-funded Warrant equal to $1.699, the price per Share, less $0.001.. The Shares, Pre-funded Warrants and the shares issuable upon exercise of the Pre-funded Warrants were offered and sold pursuant to the Company’s effective registration statement on Form S-3 (Form No. 333-255476), which was declared effective by the Securities and Exchange Commission on May 24, 2021, and the base prospectus and prospectus supplement included therein.

The Pre-funded Warrants were sold, in lieu of shares of Common Stock, to the Investor whose purchase of shares of Common Stok in the Registered Offering would otherwise result in such Investor, together with its affiliates and certain related parties, beneficially owning more than 4.99% (or, at such Investor’s option upon issuance 9.99%) of the Company’s outstanding Common Stock immediately following the consumption of the Registered Offering. The Pre-funded Warrants have an exercise price of $0.001 per share, became exercisable upon issuance and remain exercisable until exercised in full.

The Registered Offering closed on October 30, 2023. The Company intends to use the net proceeds from the Registered Offering for general corporate purposes and working capital requirements, which may include, among other things, the advancement of its product candidates to obtain regulatory approval from the Food and Drug Administration.

In a concurrent private placement, pursuant to the terms of the Purchase Agreement, the Company also agreed to issue and sell unregistered warrants (the “Warrants”) to purchase up to 2,588,236 shares of Common Stock, at an offering price of $0.125 per Warrant to purchase one share of Common Stock (the “Private Placement” and, together with the Registered Offering, the “Offerings”) (which offering price is included in the purchase price per Share or Pre-funded warrant). The Warrants have an exercise price of $1.58 per share (subject to customary adjustments as set forth in the Warrants), are exercisable upon issuance and will expire five and one-half years from the date of issuance. The Warrants contain customary anti-dilution adjustments to the exercise price, including for share splits, share dividends, rights offering and pro rata distributions.

The Private Placement also closed on October 30, 2023, concurrently with the Registered Offering. The Company received approximately $4.4 million in gross proceeds from the Offerings, before deducting placement agency fees and offering expenses.

A holder (together with its affiliates) may not exercise any portion of the Pre-funded Warrants or Warrants to the extent that the holder would own more than 4.99% (or, at the purchaser’s option upon issuance, 9.99%) of the Company’s outstanding Common Stock immediately after exercise (the “Beneficial Ownership Limitation”). However, upon at least 61 days’ prior notice from the holder to the Company, a holder may increase or decrease the Beneficial Ownership Limitation in accordance with the terms of the Pre-funded Warrants or Warrant, provided that it does not exceed 9.99%.

The Purchase Agreement contains customary representations and warranties and agreements of the Company and the Investor and customary indemnification rights and obligations of the parties. Pursuant to the terms of the Purchase Agreement, the Company has agreed to certain restrictions on the issuance and sale of its Common Stock or Common Stock Equivalents (as defined in the Purchase Agreement) during the 45-day period following the closing of the offering. In addition, pursuant to the terms of the Purchase Agreement, the Company will be required to file a resale registration statement with the U.S. Securities and Exchange Commission to register the sale of the shares issuable upon exercise of the Warrants.

H.C. Wainwright & Co., LLC (“Wainwright”) acted as the exclusive placement agent in connection with the Offerings under an Engagement Letter, dated as of October 9, 2023, between the Company and Wainwright (the “Engagement Letter”). Pursuant to the Engagement Letter, Wainwright was paid a cash fee equal to 7.0% of the gross proceeds received by the Company in the Offerings, a management fee equal to 1.0% of the gross proceeds of the Offering, $75,000 for non-accountable expenses and a clearing fee of $15,950. In addition, under the terms of the Engagement Letter, the Company issued to Wainwright (or its designees) warrants to purchase up to 155,294 shares of Common Stock (the “Wainwright Warrants”). The Wainwright Warrants have substantially the same terms as the Warrants, except that the Wainwright Warrants will expire five years from the commencement of the sales of the Offerings and have an exercise price of $2.125 per share (subject to customary adjustment as set forth in the Wainwright Warrants), representing 125% of the purchase price per Share in the Registered Offering.

The Purchase Agreement has been filed as an exhibit to this Current Report on Form 8-K to provide the investors and stockholders with information regarding its terms. It is not intended to provide any other factual information about the parties to the Purchase Agreement or any of their respective affiliates. The representations, warranties and covenants in the Purchase Agreement were made only for the purposes of such agreement and as of specified dates, were solely for the benefit of the parties to the Purchase Agreement and may be subject to limitations agreed upon by the parties. The representations and warranties may have been made for the purposes of allocating contractual risk between the parties to the Purchase Agreement instead of establishing these matters as facts and may be subject to standards of materiality applicable to the parties that differ from those applicable to investors. Investors are not third-party beneficiaries under the Purchase Agreement. Accordingly, such representations, warranties and covenants may not accurately represent the current state of the Company’s affairs at any time.

The foregoing descriptions of the Purchase Agreement, the Pre-funded Warrants, the Warrants and the Wainwright Warrants are subject to, and qualified in their entirety by reference to the full text of the agreements, copies of which (or forms thereof) are attached hereto as Exhibits 10.1, 10.2, 10.3 and 10.4, respectively, and are incorporated herein by reference.

A copy of the opinion of McGuireWoods LLP relating to the validity of the issuance and sale of the Shares and the Pre-funded Warrants is attached as Exhibit 5.1 hereto.

The information contained above in Item 1.01 relating to the Private Placement, other than information relating solely to the Registered Offering, the Shares and the Pre-funded Warrants, is hereby incorporated by reference into this Item 3.02. Based in part upon the representations of the Investor in the Purchase Agreement, the offering and sale of the Warrants is exempt from registration under Section 4(a)(2) of the Securities Act of 1933, as amended (the “Securities Act”), Rule 506 of Regulation D promulgated under the Securities Act, and corresponding provisions of state securities or “blue sky” laws. The sale of the Warrants by the Company in the Private Placement and the Wainwright Warrants has not been registered under the Securities Act or any state securities laws and the Securities may not be offered or sold in the United States absent registration with the SEC or an applicable exemption from the registration requirements. The sale of such securities did not involve a public offering and was made without general solicitation or general advertising. In the Purchase Agreement, the Investor represented, among other things, that it is and, on each date on which it exercises any Warrants, will be either (i) an accredited investor, as such term is defined in Rule 501(a) of Regulation D under the Securities Act, or (ii) a “qualified institutional buyer” as defined in Rule 144A(a) under the Securities Act, and it is acquiring the Warrants for investment purposes only and not with a view to any resale, distribution or other disposition of the Warrants in violation of the United States federal securities laws.

This Current Report on Form 8-K does not constitute an offer to sell any securities or a solicitation of an offer to buy any securities, nor shall there be any sale of any securities in any state or jurisdiction in which such an offer, solicitation or sale would be unlawful prior to registration or qualification under the securities laws of any such state or jurisdiction.

On October 26, 2023, the company issued a press release announcing the Registered Offering and the Private Placement. The full text of the press release is attached as Exhibit 99.1 to this Current Report on Form 8-K and incorporated herein by reference.

On October 30, 2023, the Company issued a press release announcing the closing of the Registered Offering and the Private Placement. The full text of the press release is attached as Exhibit 99.2 to this Current Report on Form 8-K and incorporated herein by reference.

(d) Exhibits.

The following exhibits are filed herewith:

Cautionary Note Regarding Forward-Looking Statements

This Current Report on Form 8-K contains “forward-looking statements” within the meaning of Section 27A of the Securities Act of 1933 and Section 21E of the Securities Exchange Act of 1934, as amended, that involve substantial risks and uncertainties. All statements, other than statements of historical facts, contained in this Current Report on Form 8-K are forward-looking statements. Forward-looking statements can be identified by the use of the words “anticipate,” “believe,” “estimate,” “expect,” “intend,” “may,” “plan,” “predict,” “project,” target,” “will,” “would,” “could,” “should,” “continue,” and other similar expressions. Actual events or results may differ materially from those described in this Current Report on Form 8-K due to a number of risks and uncertainties including, among other things, the development stage of the Company’s primary product candidates and the related risks involved in drug development, clinical trials and the uncertainties around regulatory reviews and approvals; other business effects, including the effects of industry, market, economic, political or regulatory conditions; as well as other risks described in Part 1, Item 1A, “Risk Factors,” in the company’s Annual Report on Form 10-K, filed on March 30, 2023, subsequent Quarterly Reports on Form 10-Q and our other filings with the Securities and Exchange Commission (the “SEC”). The forward-looking statements in this Current Report on Form 8-K represent the Company’s views as of the date of this Current Report on Form 8-K. The Company anticipates that subsequent events and developments will cause its views to change. However, while it may elect to update these forward-looking statements at some point in the future, it has no current intention of doing so except to the extent required by applicable law. You should, therefore, not rely on these forward-looking statements as representing the Company’s views as of any date subsequent to the date of this Current Report on Form 8-K.

SIGNATURES

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