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Mustang Bio, Inc.

(Name of Registrant as Specified In Its Charter)

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See the reverse side of this notice to obtain proxy materials and voting instructions. *** Exercise Your Right to Vote *** Important Notice Regarding the Availability of Proxy Materials for the Stockholder Meeting to Be Held on <mtgdate>. You are receiving this communication because you hold shares in the above named company. This is not a ballot. You cannot use this notice to vote these shares. This communication presents only an overview of the more complete proxy materials that are available to you on the Internet. You may view the proxy materials online at www.proxyvote.com or easily request a paper copy (see reverse side). We encourage you to access and review all of the important information contained in the proxy materials before voting. Meeting Information Meeting Type: <mtgtype> For holders as of: <recdate> Date: Time: <mtgtime> Location: 0000462934_1 R1.0.1.18 MUSTANG BIO, INC. MUSTANG BIO, INC. 377 Plantation Street Worcester, Massachusetts 01605 Annual Meeting April 20, 2020 June 17, 2020 June 17, 2020 3:00 PM EDT Alston & Bird LLP* 90 Park Avenue New York, NY 10016





Please Choose One of the Following Voting Methods Vote In Person: Many stockholder meetings have attendance requirements including, but not limited to, the possession of an attendance ticket issued by the entity holding the meeting. Please check the meeting materials for any special requirements for meeting attendance. At the meeting, you will need to request a ballot to vote these shares. Vote By Internet: To vote now by Internet, go to www.proxyvote.com. Have the information that is printed in the box marked by the arrow available and follow the instructions. Vote By Mail: You can vote by mail by requesting a paper copy of the materials, which will include a proxy card. How To Vote Before You Vote How to Access the Proxy Materials Proxy Materials Available to VIEW or RECEIVE: How to View Online: Have the information that is printed in the box marked by the arrow (located on the following page) and visit: www.proxyvote.com. How to Request and Receive a PAPER or E-MAIL Copy: If you want to receive a paper or e-mail copy of these documents, you must request one. There is NO charge for requesting a copy. Please choose one of the following methods to make your request: 1) BY INTERNET: www.proxyvote.com 2) BY TELEPHONE: 1-800-579-1639 3) BY E-MAIL*: sendmaterial@proxyvote.com * If requesting materials by e-mail, please send a blank e-mail with the information that is printed in the box marked by the arrow (located on the following page) in the subject line. 0000462934_2 R1.0.1.18 1. Annual Report 2. Notice & Proxy Statement Requests, instructions and other inquiries sent to this e-mail address will NOT be forwarded to your investment advisor. Please make the request as instructed above on or before June 03, 2020 to facilitate timely delivery.





Voting items 0000462934_3 R1.0.1.18 The Board of Directors recommends you vote FOR the following: 1. Election of Directors Nominees 01 Michael S. Weiss 02 Lindsay Rosenwald, M.D. 03 Neil Herskowitz 04 Manuel Litchman, M.D. 05 Michael Zelefsky, M.D. 06 Adam J. Chill The Board of Directors recommends you vote FOR the following proposal: 2. Ratify the appointment of BDO USA, LLP as the company's independent registered public accounting firm for the year ending December 31, 2020. The Board of Directors recommends you vote AGAINST the following proposal: 3. A shareholder proposal on an amendment to the Company's articles/bylaws to require majority vote in director elections. NOTE: Such other business as may properly come before the meeting or any adjournment thereof. *Depending on concerns about the coronavirus or COVID-19, we might hold a Virtual Annual Meeting instead of holding the meeting in New York. The Company would publicly announce a determination to hold a Virtual Annual Meeting in a press release available at http://www.mustangbio.com as soon as practicable before the meeting. In that event, the 2020 Annual Meeting of Stockholders would be conducted solely virtually, at the above date and time, via live audio webcast. You or your proxyholder could participate, vote and examine our stocklist at the Virtual Annual Meeting by visiting www.virtualshareholdermeeting.com/MBIO2020 and using your 16 digit control number, but only if the meeting is not held in New York.





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