Moleculin CFO settles RSUs; 5,023 shares withheld for taxes

Rhea-AI Filing Summary

Moleculin Biotech (MBRX) reported an officer equity transaction. On 11/04/2025, Chief Financial Officer Jonathan P. Foster settled 20,625 restricted stock units that converted into common stock on a one-for-one basis (code M).

To cover taxes upon vesting, 5,023 shares were withheld at a price of $0.497 per share. Following these transactions, Mr. Foster directly owns 303,189 shares of Moleculin common stock.

The RSUs relate to an award granted on November 4, 2024 of 82,500 RSUs, vesting in four equal annual installments beginning on the first anniversary of the grant date.

Insider Trade Summary

20,625 shares exercised/converted

Mixed 3 txns

Insider Foster Jonathan P.

Role Chief Financial Officer

Type	Security	Shares	Price	Value
Exercise	Restricted Stock Units	20,625	$0.00	--
Exercise	Common Stock	20,625	$0.00	--
Exercise	Common Stock	5,023	$0.497	$2K

Holdings After Transaction: Restricted Stock Units — 1,017,695 shares (Direct); Common Stock — 308,212 shares (Direct)

Footnotes (1)

1. Restricted stock units convert into common stock on a one-for-one basis. Shares withheld for payment of taxes upon vesting of restricted stock unit awards. On November 4, 2024, the reporting person was granted 82,500 restricted stock units, vesting in four equal annual installments beginning on the first anniversary of the grant date.

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^*

Foster Jonathan P.

(Last) (First) (Middle)

C/O MOLECULIN BIOTECH, INC.

5300 MEMORIAL DR., SUITE 950

(Street)

HOUSTON TX 77007

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
Moleculin Biotech, Inc. [ MBRX ]

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

	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	Chief Financial Officer

3. Date of Earliest Transaction (Month/Day/Year)
11/04/2025

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

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

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

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	11/04/2025		M		20,625	A	(1)	308,212	D
Common Stock	11/04/2025		M		5,023(2)	D	$0.497	303,189	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
Restricted Stock Units	(1)	11/04/2025		M			20,625	(3)	(3)	Common Stock	20,625	$0	1,017,695	D

Explanation of Responses:

1. Restricted stock units convert into common stock on a one-for-one basis.

2. Shares withheld for payment of taxes upon vesting of restricted stock unit awards.

3. On November 4, 2024, the reporting person was granted 82,500 restricted stock units, vesting in four equal annual installments beginning on the first anniversary of the grant date.

	/s/ Jonathan P. Foster	11/06/2025
	** 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.

FAQ

What did MBRX disclose about insider activity?

The CFO reported settlement of 20,625 RSUs into common stock on 11/04/2025 and tax share withholding of 5,023 shares at $0.497.

How many MBRX shares does the CFO own after this transaction?

After the reported transactions, the CFO directly owns 303,189 shares of common stock.

What is the source of the 20,625 MBRX shares acquired?

They came from restricted stock units converting into common stock on a one-for-one basis (transaction code M).

Why were 5,023 MBRX shares disposed of?

They were withheld for taxes upon vesting of the RSU award at a price of $0.497 per share.

What are the vesting terms of the CFO’s RSU grant?

An award of 82,500 RSUs was granted on Nov 4, 2024, vesting in four equal annual installments beginning on the first anniversary.

What is the CFO’s role at MBRX?

He is the company’s Chief Financial Officer.