Moleculin (MBRX) CSO vests 8,750; 2,131 withheld at $0.497

Moleculin Biotech (MBRX) disclosed an insider equity transaction by its Chief Science Officer.

Rhea-AI Filing Summary

Moleculin Biotech (MBRX) disclosed an insider equity transaction by its Chief Science Officer. On 11/04/2025, 8,750 restricted stock units converted to common stock, and 2,131 shares were withheld at $0.497 for taxes upon vesting. Following these transactions, the reporting person beneficially owned 16,771 shares directly. Derivative holdings show 95,508 restricted stock units remaining. The RSUs relate to a 35,000-unit grant made on November 4, 2024, scheduled to vest in four equal annual installments beginning on the first anniversary of the grant date.

Insider Trade Summary

8,750 shares exercised/converted

Exercise 3 txns

Insider PICKER DONALD H

Role Chief Science Officer

Type	Security	Shares	Price	Value
Exercise	Restricted Stock Units	8,750	$0.00	$0.00
Exercise	Common Stock	8,750	$0.00	$0.00
Exercise Price or Tax Liability	Common Stock	2,131	$0.497	$1K

Holdings After Transaction: Restricted Stock Units — 95,508 contracts (Direct); Common Stock — 16,771 shares (Direct)

Footnotes (3)

1. F1. Restricted stock units convert into common stock on a one-for-one basis.
2. F2. Shares withheld for payment of taxes upon vesting of restricted stock unit awards.
3. F3. On November 4, 2024, the reporting person was granted 35,000 restricted stock units, vesting in four equal annual installments beginning on the first anniversary of the grant date

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

What did MBRX report in this Form 4?

The Chief Science Officer had 8,750 restricted stock units convert into common stock on 11/04/2025, with 2,131 shares withheld at $0.497 for taxes.

How many MBRX shares does the insider own after the transaction?

The filing states 16,771 shares beneficially owned directly after the reported transactions.

What is the insider’s remaining RSU balance at MBRX?

The filing lists 95,508 restricted stock units beneficially owned following the reported transaction.

What was the source of the 2,131 shares withheld?

They were withheld to cover taxes upon vesting of restricted stock unit awards at a price of $0.497 per share.

What is the vesting schedule for the RSUs mentioned?

The 35,000 RSUs granted on November 4, 2024 vest in four equal annual installments beginning on the first anniversary of the grant date.

What is the insider’s role at Moleculin Biotech (MBRX)?

The reporting person serves as Chief Science Officer.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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Accepted by SEC EDGAR 11/06/2025 - 08:25 PM Learn about SEC filing dates

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^*

PICKER DONALD H

(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 Science 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		8,750	A	(1)	18,902	D
Common Stock	11/04/2025		F		2,131(2)	D	$0.497	16,771	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			8,750	(3)	(3)	Common Stock	8,750	$0	95,508	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 35,000 restricted stock units, vesting in four equal annual installments beginning on the first anniversary of the grant date

	/s/ Jonathan P. Foster by Power of Attorney	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.