STOCK TITAN

Moleculin Biotech (MBRX) CEO reports RSU vesting, tax-share withholding and retained stake

Filing Impact
(Neutral)
Filing Sentiment
(Neutral)
Form Type
4

Rhea-AI Filing Summary

Moleculin Biotech, Inc. CEO and President Walter V. Klemp reported routine equity compensation activity involving restricted stock units and related tax withholding. On June 20 and June 22, restricted stock units converted into a total of 510 shares of common stock at a conversion price of $0.00 per share. To cover tax obligations on these vestings, a total of 125 common shares were disposed of via tax-withholding transactions, rather than open-market sales. After these transactions, Klemp directly held 31,007 shares of common stock and continued to hold a substantial equity position through 326,336 restricted stock units, as well as 250,002 shares of common stock underlying Series E warrants.

Positive

  • None.

Negative

  • None.
Insider KLEMP WALTER V
Role CEO and President
Type Security Shares Price Value
Exercise Restricted Stock Units 360 $0.00 --
Exercise Common Stock 360 $0.00 --
Tax Withholding Common Stock 88 $3.12 $274.56
Exercise Restricted Stock Units 150 $0.00 --
Exercise Common Stock 150 $0.00 --
Tax Withholding Common Stock 37 $2.88 $106.56
Holdings After Transaction: Restricted Stock Units — 326,336 shares (Direct, null); Common Stock — 31,088 shares (Direct, null)
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 June 20, 2022, the reporting person was granted 600 restricted stock units, vesting in four equal annual installments beginning on the first anniversary of the grant date. On June 22, 2023, the reporting person was granted 1,439 restricted stock units, vesting in four equal annual installments beginning on the first anniversary of the grant date. Includes 250,002 shares of common stock underlying Series E warrants to purchase common stock.
RSU conversions 510 shares Restricted stock units converted into common stock on June 20 and June 22
Tax-withheld shares 125 shares Common shares delivered to cover tax liabilities on RSU vesting
Common shares held 31,007 shares Direct common stock holdings after transactions
RSUs outstanding 326,336 units Restricted stock units remaining after reported conversions
Series E warrants underlying 250,002 shares Shares of common stock underlying Series E warrants
Tax disposition prices $3.12 and $2.88 per share Prices for shares delivered to cover tax liabilities
Restricted stock units financial
"Restricted stock units convert into common stock on a one-for-one basis."
Restricted stock units are a type of company reward where employees are promised shares of stock, but they only fully own these shares after meeting certain conditions, like staying with the company for a set time. They matter because they can become valuable assets and are often used to motivate employees to help the company succeed.
tax-withholding disposition financial
"Payment of exercise price or tax liability by delivering securities"
A tax-withholding disposition is an event or transaction—such as selling or transferring securities, exercising options, or receiving compensation—that triggers a requirement to hold back part of the payment and remit it to tax authorities. It matters to investors because it reduces the cash they receive immediately and can change the timing and amount of taxable income, like a cashier taking a portion of your sale proceeds to pay taxes before you get the rest.
derivative security financial
"Exercise or conversion of derivative security"
A derivative security is a financial contract whose value comes from the price or performance of something else, such as a stock, bond, commodity, or market index. For investors it acts like an insurance policy or a wager: it can be used to protect against losses, lock in prices, or amplify gains and losses, so it can change a portfolio’s risk and potential return without owning the underlying asset directly.
Series E warrants financial
"Includes 250,002 shares of common stock underlying Series E warrants to purchase common stock."
See more from StockTitan in Google Search and AI answers. Adds StockTitan as a preferred source · opens Google
Add on Google
Learn about SEC filing dates
SEC Form 4
FORM 4UNITED 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*
KLEMP WALTER V

(Last)(First)(Middle)
C/O MOLECULIN BIOTECH, INC.
5300 MEMORIAL DR., SUITE 950

(Street)
HOUSTON TEXAS 77007

(City)(State)(Zip)

UNITED STATES

(Country)
2. Issuer Name and Ticker or Trading Symbol
Moleculin Biotech, Inc. [ MBRX ]
5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)
XDirector10% Owner
XOfficer (give title below)Other (specify below)
CEO and President
2a. Foreign Trading Symbol
3. Date of Earliest Transaction (Month/Day/Year)
06/20/2026
6. Individual or Joint/Group Filing (Check Applicable Line)
XForm filed by One Reporting Person
Form filed by More than One Reporting Person
4. If Amendment, Date of Original Filed (Month/Day/Year)

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)
CodeVAmount(A) or (D)Price
Common Stock06/20/2026M150A(1)30,765D
Common Stock06/20/2026F37(2)D$2.8830,728D
Common Stock06/22/2026M360A(1)31,088D
Common Stock06/22/2026F88(2)D$3.1231,007D
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)
CodeV(A)(D)Date ExercisableExpiration DateTitleAmount or Number of Shares
Restricted Stock Units(1)06/20/2026M150 (3) (3)Common Stock150$0326,696(5)D
Restricted Stock Units(1)06/22/2026M360 (4) (4)Common Stock360$0326,336(5)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 600 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 1,439 restricted stock units, vesting in four equal annual installments beginning on the first anniversary of the grant date.
5. Includes 250,002 shares of common stock underlying Series E warrants to purchase common stock.
/s/ Jonathan P. Foster by Power of Attorney06/24/2026
** Signature of Reporting PersonDate
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.
* Form 4: SEC 1474 (03-26)

FAQ

What insider transactions did Moleculin Biotech (MBRX) report for its CEO?

Moleculin Biotech CEO Walter V. Klemp reported routine equity compensation activity. Restricted stock units converted into 510 common shares, and 125 shares were withheld to cover taxes, with no open-market purchases or sales disclosed.

How many Moleculin Biotech (MBRX) shares did the CEO acquire through exercises?

Walter V. Klemp acquired 510 shares of Moleculin Biotech common stock through the conversion of restricted stock units. These derivative exercises occurred on June 20 and June 22 and reflect equity awards vesting rather than open-market buying activity.

How many Moleculin Biotech (MBRX) shares were withheld for the CEO’s taxes?

A total of 125 common shares were withheld to pay taxes on vesting restricted stock units. These Form 4 transactions are coded as tax-withholding dispositions, meaning the shares were delivered for tax liabilities, not sold in the open market.

What are the CEO’s Moleculin Biotech (MBRX) common stock holdings after these transactions?

Following the reported transactions, Walter V. Klemp directly held 31,007 shares of Moleculin Biotech common stock. This figure reflects his position after both the restricted stock unit conversions and the related tax-withholding share dispositions.

What derivative equity interests in Moleculin Biotech (MBRX) does the CEO still hold?

After the reported vestings, Walter V. Klemp continued to hold 326,336 restricted stock units and 250,002 shares of common stock underlying Series E warrants. These instruments provide additional potential equity exposure beyond his directly held common shares.

Were the Moleculin Biotech (MBRX) insider transactions open-market buys or sells?

The filing shows derivative exercises of restricted stock units into common shares and tax-withholding dispositions. The transactions involve equity awards vesting and shares delivered for taxes, rather than discretionary open-market purchases or sales by the CEO.