Mustang Bio (NASDAQ: MBIO) CEO reports 19-share tax withholding event

Rhea-AI Filing Summary

Mustang Bio, Inc.’s President, CEO and Interim CFO Manuel Litchman reported a small, routine tax-withholding transaction. On April 24, 2026, 19 shares of common stock were relinquished at $0.75 per share to cover tax liability tied to the vesting of restricted stock units.

This was not an open-market sale but a payment of taxes using shares. After this transaction, Litchman directly owned 1,615 shares of Mustang Bio common stock.

Insider Trade Summary

1 transaction reported

Mixed 1 txn

Insider Litchman Manuel MD

Role President, CEO and Interim CFO

Type	Security	Shares	Price	Value
Tax Withholding	COMMON STOCK	19	$0.75	$14.25

Holdings After Transaction: COMMON STOCK — 1,615 shares (Direct, null)

Footnotes (1)

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Key Figures

Tax-withholding shares: 19 shares Price per share: $0.75 per share Shares owned after transaction: 1,615 shares

3 metrics

Tax-withholding shares 19 shares Relinquished to cover tax liability on RSU vesting at $0.75/share

Price per share $0.75 per share Value used for the 19-share tax-withholding disposition

Shares owned after transaction 1,615 shares Direct Mustang Bio common stock holdings following Form 4 event

Key Terms

restricted stock units, tax liability, tax-withholding disposition, Form 4

4 terms

restricted stock units financial

"delivery of shares of common stock upon the vesting of restricted stock units"

Restricted stock units are a type of company reward where employees are promised shares of stock, but they only fully own these shares after meeting certain conditions, like staying with the company for a set time. They matter because they can become valuable assets and are often used to motivate employees to help the company succeed.

tax liability financial

"relinquished to cover tax liability associated with the delivery of shares"

tax-withholding disposition financial

"transaction_action": "tax-withholding disposition""

A tax-withholding disposition is an event or transaction—such as selling or transferring securities, exercising options, or receiving compensation—that triggers a requirement to hold back part of the payment and remit it to tax authorities. It matters to investors because it reduces the cash they receive immediately and can change the timing and amount of taxable income, like a cashier taking a portion of your sale proceeds to pay taxes before you get the rest.

Form 4 regulatory

"INSIDER FILING DATA (Form 4):"

Form 4 is a official document that company insiders, such as executives or major shareholders, file with regulators whenever they buy or sell company shares. It provides transparency about how those with inside knowledge are trading, helping investors see if insiders are confident in the company's prospects or may be selling for personal reasons. This information can influence investor decisions by revealing insiders' perspectives on the company's value.

Form 4 Insider Transactions: What Each Field Means →

SEC Form 4

FORM 4

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940

OMB APPROVAL

OMB Number:			3235-0287
Estimated average burden
hours per response:			0.5

Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.

1. Name and Address of Reporting Person^*

Litchman Manuel MD

(Last) (First) (Middle)

95 SAWYER ROAD, SUITE 110

(Street)

WALTHAM MASSACHUSETTS 02453

(City) (State) (Zip)

UNITED STATES

(Country)

2. Issuer Name and Ticker or Trading Symbol
MUSTANG BIO, INC. [ MBIO ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

X	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	President, CEO and Interim CFO

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
04/24/2026

6. Individual or Joint/Group Filing (Check Applicable Line)

X	Form filed by One Reporting Person
	Form filed by More than One Reporting Person

4. If Amendment, Date of Original Filed (Month/Day/Year)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
COMMON STOCK	04/24/2026		F		19(1)	D	$0.75	1,615	D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares

Explanation of Responses:

1. 19 shares of common stock were relinquished to cover tax liability associated with the delivery of shares of common stock upon the vesting of restricted stock units.

	/s/ Manuel Litchman, M.D.	04/27/2026
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.
* Form 4: SEC 1474 (03-26)

FAQ

What did Mustang Bio (MBIO) insider Manuel Litchman report on this Form 4?

Manuel Litchman reported relinquishing 19 Mustang Bio common shares to pay taxes on vested restricted stock units. This tax-withholding disposition is a routine administrative event rather than an open-market trade, and it slightly reduced his directly held share count.

How many Mustang Bio (MBIO) shares were involved in Manuel Litchman’s latest transaction?

The transaction involved 19 shares of Mustang Bio common stock at $0.75 per share. These shares were surrendered to satisfy tax liability from restricted stock unit vesting, not sold on the open market, making this a small, routine adjustment to his holdings.

Was Manuel Litchman’s Mustang Bio (MBIO) Form 4 a stock sale in the open market?

No, the Form 4 shows a tax-withholding disposition, not an open-market sale. Nineteen shares were relinquished to cover tax liability tied to restricted stock unit vesting, a standard mechanism used to handle tax obligations on equity compensation.

How many Mustang Bio (MBIO) shares does Manuel Litchman hold after this Form 4 transaction?

Following the tax-withholding disposition, Manuel Litchman directly holds 1,615 shares of Mustang Bio common stock. The transaction slightly reduced his position, as only 19 shares were relinquished to cover taxes associated with the vesting of restricted stock units.

What does transaction code "F" mean in the Mustang Bio (MBIO) Form 4 filing?

Transaction code “F” indicates shares were used to satisfy tax obligations or exercise costs. In this Mustang Bio filing, 19 shares were relinquished to pay tax liability arising from restricted stock unit vesting, rather than being voluntarily sold on the open market.