Miami International Holdings (MIAX) officer boosts share holdings

Rhea-AI Filing Summary

Miami International Holdings, Inc. executive leadership reported multiple stock option exercises that increased direct ownership of the company’s common stock. The reporting person is an officer serving as EVP and Chief Strategy Officer.

On 12/16/2025, the officer exercised incentive stock options at an exercise price of $12 per share in three separate transactions for 16,666, 8,333, and 8,333 shares of common stock. Following these transactions, the officer beneficially owned 345,031 shares of common stock directly. The derivative securities table shows the related incentive stock option positions reduced to 0 derivative securities beneficially owned after the exercises, and the options are described as fully vested.

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

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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^*

Brown Shelly

(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)

	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	EVP, Chief Strategy Officer

3. Date of Earliest Transaction (Month/Day/Year)
12/16/2025

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	12/16/2025		M		16,666	A	$12	328,365	D
Common Stock	12/16/2025		M		8,333	A	$12	336,698	D
Common Stock	12/16/2025		M		8,333	A	$12	345,031	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
Incentive Stock Option (Right to Buy)	$12	12/16/2025		M			16,666	(1)	08/02/2026	Common Stock	16,666	$0	0	D
Incentive Stock Option (Right to Buy)	$12	12/16/2025		M			8,333	(1)	10/12/2027	Common Stock	8,333	$0	0	D
Incentive Stock Option (Right to Buy)	$12	12/16/2025		M			8,333	(1)	05/17/2028	Common Stock	8,333	$0	0	D

Explanation of Responses:

1. The options are fully vested.

Remarks:

	/s/ Barbara J. Comly, Attorney-in-fact	12/17/2025
	** 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.
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FAQ

What insider transaction did MIAX report in this Form 4 filing?

The filing reports that an officer of Miami International Holdings, Inc. exercised incentive stock options into shares of the company’s common stock on 12/16/2025.

How many MIAX common shares were acquired in the reported transactions?

The Form 4 shows three option exercises for common stock at $12 per share, covering 16,666, 8,333, and 8,333 shares.

What is the role of the reporting person at Miami International Holdings (MIAX)?

The reporting person is identified as an officer of Miami International Holdings, Inc., holding the title EVP, Chief Strategy Officer.

How many MIAX shares does the insider own after these option exercises?

After the reported transactions, the officer beneficially owned 345,031 shares of Miami International Holdings, Inc. common stock directly.

What was the exercise price of the MIAX incentive stock options?

Each incentive stock option reported in the filing had an exercise price of $12 per share of common stock.

What happened to the stock options after the reported MIAX transactions?

In the derivative securities table, each related incentive stock option shows 0 derivative securities beneficially owned following the exercises, and a footnote states that the options are fully vested.

Is the MIAX Form 4 filed by one or multiple reporting persons?

The filing indicates it is a Form filed by One Reporting Person, not a joint or group filing.