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

Rhea-AI Filing Summary

Walter V. Klemp, CEO, President and Director of Moleculin Biotech (MBRX), reported multiple insider transactions on June 20-23, 2025:

• Acquired 3,750 shares from RSU vesting on June 20, with 914 shares withheld for taxes
• Acquired 8,990 shares from RSU vesting on June 22, with 2,190 shares withheld for taxes
• Purchased 675,675 common shares at $0.37 per share in a public offering on June 23
• Acquired Series E warrants to purchase 2,027,025 additional shares at $0.37/share

Following these transactions, Klemp directly owns 743,607 common shares and 2,409,481 derivative securities. The Series E warrants will be exercisable upon stockholder approval and expire 5 years after approval. These transactions demonstrate significant insider investment in the company, particularly through participation in the public offering.

Positive

• CEO Walter Klemp made a significant open market purchase of 675,675 shares at $0.37 per share, representing a substantial personal investment of approximately $250,000
• CEO acquired Series E warrants to purchase an additional 2,027,025 shares at $0.37, demonstrating strong long-term confidence in the company

Negative

• None.

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
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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^*

KLEMP WALTER V

(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)

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

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		3,750	A	(1)	62,046	D
Common Stock	06/20/2025		F		914(2)	D	$0.267	61,132	D
Common Stock	06/22/2025		M		8,990	A	(1)	70,122	D
Common Stock	06/22/2025		F		2,190(2)	D	$0.267	67,932	D
Common Stock	06/23/2025		P		675,675	A	$0.37(5)	743,607	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			3,750	(3)	(3)	Common Stock	3,750	$0	391,446	D
Restricted Stock Units	(1)	06/22/2025		M			8,990	(4)	(4)	Common Stock	8,990	$0	382,456	D
Series E Warrants	$0.37	06/23/2025		P			2,027,025	(5)	(5)	Common Stock	2,027,025	(5)	2,409,481	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 15,000 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 35,959 restricted stock units, vesting in four equal annual installments beginning on the first anniversary of the grant date.

5. On June 23, 2025, the reporting person acquired 675,675 shares of common stock and Series E warrants to purchase 2,027,025 shares of common stock at a purchase price of $0.37 per share and accompanying warrants in a public offering. The Series E warrants will be exercisable beginning on the effective date of stockholder approval of the issuance of the shares upon exercise of the Series E warrants and will expire five years from the date of such approval.

	/s/ Jonathan P. Foster by Power of Attorney	06/23/2025
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
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** 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 CEO Walter Klemp purchase in the June 2025 public offering?

CEO Walter Klemp purchased 675,675 shares of MBRX common stock at $0.37 per share in a public offering on June 23, 2025. Along with the shares, he also received Series E warrants to purchase an additional 2,027,025 shares.

What is the exercise price of MBRX's Series E warrants issued in June 2025?

The Series E warrants have an exercise price of $0.37 per share. These warrants will be exercisable after stockholder approval and will expire five years from the approval date.

How many restricted stock units (RSUs) vested for MBRX's CEO in June 2025?

In June 2025, a total of 12,740 restricted stock units (RSUs) vested for CEO Walter Klemp, consisting of 3,750 RSUs that vested on June 20, 2025, and 8,990 RSUs that vested on June 22, 2025.

What is the total number of MBRX shares beneficially owned by Walter Klemp after the June 2025 transactions?

Following all reported transactions in June 2025, Walter Klemp directly owned 743,607 shares of MBRX common stock. Additionally, he held Series E warrants for 2,027,025 shares and 382,456 unvested restricted stock units.

How many MBRX shares were withheld for tax purposes from CEO Klemp's RSU vestings?

A total of 3,104 shares were withheld for tax purposes, consisting of 914 shares withheld on June 20, 2025, and 2,190 shares withheld on June 22, 2025, at a price of $0.267 per share.