Miami International (MIAX) CEO surrenders shares for tax withholding

Rhea-AI Filing Summary

Miami International Holdings, Inc. Chairman and CEO Thomas P. Gallagher, also a director, reported a Form 4 transaction involving company common stock. On February 10, 2026, 50,100 shares were disposed of at $41.33 per share in a transaction coded “F.”

According to the footnote, these shares were surrendered back to the company to satisfy tax withholding and remittance obligations related to the net settlement of restricted stock awards and do not represent an open-market sale. After this tax-withholding disposition, Gallagher directly beneficially owned 535,863 shares of common stock.

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^*

Gallagher Thomas P.

(Last) (First) (Middle)

C/O MIAMI INTERNATIONAL HOLDINGS, INC

7 ROSZEL ROAD, SUITE 1A

(Street)

PRINCETON NJ 08540

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
MIAMI INTERNATIONAL HOLDINGS, INC. [ MIAX ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

X	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	Chairman & CEO

3. Date of Earliest Transaction (Month/Day/Year)
02/10/2026

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	02/10/2026		F		50,100(1)	D	$41.33	535,863	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

Explanation of Responses:

1. Represents shares that have been surrendered to the Company to satisfy tax withholding and remittance obligations in connection with the net settlement of restricted stock awards and does not represent a sale by the reporting person.

Remarks:

	/s/ Barbara J. Comly, Attorney-in-fact	02/12/2026
	** 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).
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FAQ

What did MIAX Chairman and CEO Thomas P. Gallagher report on this Form 4?

Thomas P. Gallagher reported a disposition of 50,100 shares of Miami International Holdings common stock. The shares were surrendered to the company to cover tax withholding and remittance obligations arising from net-settled restricted stock awards, rather than being sold on the open market.

Was the MIAX Form 4 transaction a sale of shares by Thomas P. Gallagher?

The Form 4 states the transaction does not represent a sale by Thomas P. Gallagher. Instead, the 50,100 shares were surrendered back to Miami International Holdings to satisfy tax withholding and remittance obligations tied to the net settlement of restricted stock awards.

How many MIAX shares did Thomas P. Gallagher dispose of and at what price?

The filing shows 50,100 shares of Miami International Holdings common stock were disposed of at $41.33 per share. The transaction is coded “F,” indicating payment of tax liability by delivering securities instead of an ordinary market sale transaction.

How many MIAX shares does Thomas P. Gallagher own after this Form 4 transaction?

After the reported tax-withholding disposition, Thomas P. Gallagher beneficially owns 535,863 shares of Miami International Holdings common stock. The filing classifies this ownership as direct, meaning the shares are held in his own name rather than through an intermediate entity.

What does Transaction Code "F" mean in the MIAX Form 4 filing?

Transaction Code “F” means shares were used to pay an exercise price or tax liability. In this case, 50,100 Miami International Holdings shares were surrendered to satisfy tax withholding and remittance obligations from net-settled restricted stock awards, not sold in an open-market transaction.

What roles does Thomas P. Gallagher hold at Miami International Holdings (MIAX)?

Thomas P. Gallagher is identified as both Chairman and Chief Executive Officer of Miami International Holdings and also serves as a director. These roles are disclosed in the Form 4 relationship section, which notes his officer title as Chairman & CEO and confirms his board membership.