MUSTANG BIO, INC.

Report of Independent Registered Public Accounting Firm

To the Stockholders and Board of Directors

Mustang Bio, Inc.:

Opinion on the Financial Statements

We have audited the accompanying balance sheets of Mustang Bio, Inc. (the Company) as of December 31, 2024 and 2023, the related statements of operations, stockholders’ equity, and cash flows for the years then ended , and the related notes (collectively, the financial statements). In our opinion, the financial statements present fairly, in all material respects, the financial position of the Company as of December 31, 2024 and 2023, and the results of its operations and its cash flows for the years then ended, in conformity with U.S. generally accepted accounting principles.

Going Concern

The accompanying financial statements have been prepared assuming that the Company will continue as a going concern. As discussed in Note 1 to the financial statements, the Company’s expectation to generate operating losses and negative operating cash flows in the future, and the need for additional funding to support its planned operations raise substantial doubt about its ability to continue as a going concern. Management’s plans in regard to these matters are also described in Note 1. The financial statements do not include any adjustments that might result from the outcome of this uncertainty.

Basis for Opinion

These financial statements are the responsibility of the Company’s management. Our responsibility is to express an opinion on these financial statements based on our audits. We are a public accounting firm registered with the Public Company Accounting Oversight Board (United States) (PCAOB) and are required to be independent with respect to the Company in accordance with the U.S. federal securities laws and the applicable rules and regulations of the Securities and Exchange Commission and the PCAOB.

We conducted our audits in accordance with the standards of the PCAOB. Those standards require that we plan and perform the audit to obtain reasonable assurance about whether the financial statements are free of material misstatement, whether due to error or fraud. The Company is not required to have, nor were we engaged to perform, an audit of its internal control over financial reporting. As part of our audits, we are required to obtain an understanding of internal control over financial reporting but not for the purpose of expressing an opinion on the effectiveness of the Company’s internal control over financial reporting. Accordingly, we express no such opinion.

Our audits included performing procedures to assess the risks of material misstatement of the financial statements, whether due to error or fraud, and performing procedures that respond to those risks. Such procedures included examining, on a test basis, evidence regarding the amounts and disclosures in the financial statements. Our audits also included evaluating the accounting principles used and significant estimates made by management, as well as evaluating the overall presentation of the financial statements. We believe that our audits provide a reasonable basis for our opinion.

Critical Audit Matter

The critical audit matter communicated below is a matter arising from the current period audit of the financial statements that was communicated or required to be communicated to the audit committee and that: (1) relates to accounts or disclosures that are material to the financial statements and (2) involved our especially challenging, subjective, or complex judgments. The communication of a critical audit matter does not alter in any way our opinion on the financial statements, taken as a whole, and we are not, by communicating the critical audit matter below, providing a separate opinion on the critical audit matter or on the accounts or disclosures to which it relates.

Accounting for and fair value of the Induced Warrant Exercise

As discussed in Notes 2 and 10 to the financial statements, in October 2024, the Company recorded a deemed dividend of $7.8 million for the issuance of warrants to purchase shares of Company common stock (New Warrants) in exchange for the exercise of certain existing warrants (the Induced Warrant Exercise), which was included in the net loss attributable to Class A common and common stockholders in the calculation of net loss per share. The Company used the Black-Scholes Model to determine the estimated fair value of the New Warrants issued in the Induced Warrant Exercise.

We identified the evaluation of the Company’s accounting for the Induced Warrant Exercise and the determination of the fair value of the New Warrants as a critical audit matter. Specifically, challenging and complex auditor judgment and specialized skills and knowledge were required in evaluating the application of the relevant accounting guidance, including the conclusion that the New Warrants are equity classified and that the fair value of the New Warrants should be considered a deemed dividend in determining net loss per share, and the estimated fair value of the New Warrants due to the degree of subjectivity associated with the expected volatility assumption.

The following are the primary procedures we performed to address this critical audit matter. We inspected the Company’s accounting analysis for the transaction. We involved individuals with specialized skills and knowledge, who assisted in inspecting the underlying agreements to understand the relevant terms and conditions of the transaction and evaluating whether the Company’s accounting for the transaction was in accordance with the relevant accounting guidance. We also involved valuation professionals with specialized skills and knowledge, who assisted in:

/s/ KPMG LLP

We have served as the Company’s auditor since 2021.

Boston, Massachusetts

March 28, 2025