[Form 4] Moleculin Biotech, Inc. Insider Trading Activity

Rhea-AI Filing Summary

Donald H. Picker, Chief Science Officer of Moleculin Biotech (MBRX), reported multiple transactions involving restricted stock units (RSUs) and common stock:

• On June 20, 2025, converted 1,078 RSUs to common stock and had 263 shares withheld for tax purposes at $0.267 per share, resulting in 8,816 directly owned shares
• On June 22, 2025, converted 1,766 RSUs to common stock and had 430 shares withheld for tax purposes at $0.267 per share, resulting in 10,152 directly owned shares

These transactions stem from two RSU grants: 4,312 units granted on June 20, 2022, and 7,063 units granted on June 22, 2023, both vesting in four equal annual installments. Following these transactions, Picker maintains direct ownership of 104,258 RSUs.

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

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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)
06/20/2025

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	06/20/2025		M		1,078	A	(1)	9,079	D
Common Stock	06/20/2025		F		263(2)	D	$0.267	8,816	D
Common Stock	06/22/2025		M		1,766	A	(1)	10,582	D
Common Stock	06/22/2025		F		430(2)	D	$0.267	10,152	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)	06/20/2025		M			1,078	(3)	(3)	Common Stock	1,078	$0	106,024	D
Restricted Stock Units	(1)	06/22/2025		M			1,766	(4)	(4)	Common Stock	1,766	$0	104,258	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 June 20, 2022, the reporting person was granted 4,312 restricted stock units, vesting in four equal annual installments beginning on the first anniversary of the grant date.

4. On June 22, 2023, the reporting person was granted 7,063 restricted stock units, vesting in four equal annual installments beginning on the first anniversary of the grant date.

	/s/ Jonathan P. Foster	06/23/2025
	** 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).
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FAQ

How many MBRX shares did Chief Science Officer Donald Picker acquire on June 20, 2025?

Donald Picker acquired 1,078 shares of MBRX common stock on June 20, 2025 through the conversion of restricted stock units (RSUs). However, 263 shares were withheld for tax purposes, resulting in a net acquisition of 815 shares.

What was the vesting schedule for MBRX's RSU grant to Donald Picker in June 2022?

The RSU grant made on June 20, 2022, consisted of 4,312 restricted stock units that vest in four equal annual installments beginning on the first anniversary of the grant date.

How many MBRX restricted stock units does Donald Picker own after the June 22, 2025 transaction?

Following the reported transactions, Donald Picker owns 104,258 restricted stock units of MBRX directly, as shown in Table II of the Form 4 filing.

What is the total number of MBRX common shares Donald Picker owns after all reported transactions?

After all reported transactions on June 20 and June 22, 2025, Donald Picker directly owns 10,152 shares of MBRX common stock, as indicated in the final entry of Table I.

At what price were MBRX shares withheld for tax purposes in the June 2025 transactions?

The shares withheld for tax purposes were valued at $0.267 per share for both the June 20 and June 22, 2025 transactions.