Jonathan P. Foster - 20 Jun 2026 Form 4 Insider Report for Moleculin Biotech, Inc. (MBRX)

Reporting relationship: Chief Financial Officer
Issuer ticker: MBRX
Reported as of: 20 Jun 2026
Net transaction value: $0
SEC form: 4
Accepted by SEC: 24 Jun 2026, 21:00:21 UTC
Prior SEC filing: 20 Feb 2026
Next SEC filing: 05 Aug 2026
Source filing: View source filing
Reporting owner signature: /s/ Jonathan P. Foster

Key filing fact

Jonathan P. Foster filed Form 4 for Moleculin Biotech, Inc. (MBRX) on 24 Jun 2026.

Key facts

This page summarizes Jonathan P. Foster's Form 4 filing for Moleculin Biotech, Inc. (MBRX).
6 reported transactions and 2 derivative rows are listed below.
Accepted by SEC: 24 Jun 2026, 21:00.

Change

Previous filing in this sequence was filed on 20 Feb 2026.
Current net transaction value: $0.

Research use

This tells you what this filing adds before you inspect full transaction and derivative tables.
You can trace every row back to the original SEC filing document.

Evidence

Filed on Form 4

Ownership activity is grounded in SEC Form 4 disclosures.

View source filing

Reporting Owners (1)

CIK 0001545414 Primary reporting owner

Foster Jonathan P.

Relationship: Chief Financial Officer
Address: C/O MOLECULIN BIOTECH, INC., 5300 MEMORIAL DR., SUITE 950, HOUSTON
Signature: /s/ Jonathan P. Foster
Signature date: 24 Jun 2026

Reported non-derivative transactions

Shares, units, or other non-derivative securities reported in this filing.

MBRX transaction

Common Stock

Options Exercise

Transaction value
Shares: +109
Change %: +0.9%
Price
Shares after: 12,238
Date: 20 Jun 2026
Ownership: Direct
Footnotes: F1

MBRX transaction

Common Stock

Tax liability

Transaction value
Shares: -31
Change %: -0.25%
Price: $2.88^*
Shares after: 12,207
Date: 20 Jun 2026
Ownership: Direct
Footnotes: F2

MBRX transaction

Common Stock

Options Exercise

Transaction value
Shares: +174
Change %: +1.4%
Price
Shares after: 12,381
Date: 22 Jun 2026
Ownership: Direct
Footnotes: F1

MBRX transaction

Common Stock

Tax liability

Transaction value
Shares: -41
Change %: -0.33%
Price: $3.12^*
Shares after: 12,340
Date: 22 Jun 2026
Ownership: Direct
Footnotes: F2

Reported derivative securities

Options, warrants, convertible securities, or similar derivative positions disclosed in the filing.

MBRX transaction Derivative

Restricted Stock Units

Options Exercise

Transaction value
Shares: -109
Change %: -0.07%
Price: $0.000000^*
Shares after: 147,892
Date: 20 Jun 2026
Ownership: Direct
Underlying class: Common Stock
Underlying amount: 109
Exercise price
Footnotes: F1, F3, F5

MBRX transaction Derivative

Restricted Stock Units

Options Exercise

Transaction value
Shares: -174
Change %: -0.12%
Price: $0.000000^*
Shares after: 147,718
Date: 22 Jun 2026
Ownership: Direct
Underlying class: Common Stock
Underlying amount: 174
Exercise price
Footnotes: F1, F4, F5

^* marks a reported price that did not pass the local price check.

Additional SEC filing notes

Filing notes and footnotes

Explanation of responses 5 footnotes

Footnote F1

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

Footnote F2

Shares withheld for payment of taxes upon vesting of restricted stock unit awards.

Footnote F3

On June 20, 2022, the reporting person was granted 434 restricted stock units, vesting in four equal annual installments beginning on the first anniversary of the grant date.

Footnote F4

On June 22, 2023, the reporting person was granted 693 restricted stock units, vesting in four equal annual installments beginning on the first anniversary of the grant date.

Footnote F5

Includes 100,003 shares of common stock underlying Series E warrants to purchase common stock.