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

Rhea-AI Filing Summary

Moleculin Biotech (MBRX) reported an insider equity event by its CEO and President/Director. On 11/04/2025, 28,750 shares of common stock were acquired upon the vesting and conversion of restricted stock units (transaction code M). The filing also shows 7,001 shares were disposed (code F) to cover taxes at $0.497 per share.

Following these transactions, the executive directly beneficially owned 765,356 shares of common stock. The derivative holdings section lists 2,380,731 derivative securities beneficially owned after the reported transaction. The RSUs convert one-for-one into common stock, and the underlying grant from November 4, 2024 totals 115,000 RSUs vesting in four equal annual installments beginning on the first anniversary.

Insights

Equity compensation & insider transactions analyst

Routine RSU vesting with tax withholding; neutral impact.

The CEO’s Form 4 shows 28,750 shares issued from RSU vesting (code M) and 7,001 shares withheld for taxes (code F) at $0.497 on 11/04/2025. This aligns with a standard equity compensation schedule where RSUs convert one-for-one into common stock.

Post-transaction direct ownership stands at 765,356 common shares, while 2,380,731 derivative securities remain beneficially owned. The vesting relates to a 115,000 RSU grant from 11/04/2024, set to vest in four equal annual tranches. These are administrative insider movements; market impact typically depends on broader float and trading, which is not addressed here.

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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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^*

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)
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		28,750	A	(1)	772,357	D
Common Stock	11/04/2025		F		7,001(2)	D	$0.497	765,356	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			28,750	(3)	(3)	Common Stock	28,750	$0	2,380,731	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 115,000 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.

FAQ

What did MBRX’s CEO report on Form 4?

Vesting of 28,750 RSUs into common stock (code M) and tax withholding of 7,001 shares (code F) at $0.497 per share on 11/04/2025.

How many MBRX shares does the CEO own after the transactions?

Direct beneficial ownership is 765,356 shares of common stock after the reported transactions.

How many derivative securities does the CEO hold after the event?

The filing lists 2,380,731 derivative securities beneficially owned following the transaction.

What is the conversion ratio for the RSUs?

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

What is the vesting schedule for the RSU grant referenced?

A 115,000 RSU grant from November 4, 2024 vests in four equal annual installments beginning on the first anniversary.

What were the Form 4 transaction codes used?

Code M for RSU conversion to common stock and code F for shares withheld for taxes.