[Form 4] Miami International Holdings, Inc. Insider Trading Activity

Rhea-AI Filing Summary

Miami International Holdings insider Edward Deitzel completed option exercises and share purchases in September 2025, increasing his direct holdings. On 09/09/2025 he exercised 62,500 nonqualified options with a $12 exercise price and acquired 62,500 common shares via that exercise. The same day 38,090 shares were surrendered to the company to satisfy tax withholding related to the net settlement of those exercises; this surrender is not a sale. On 09/10/2025 he exercised 16,666 incentive stock options at $12, and on 09/11/2025 he purchased 16,666 shares at $12. Following these transactions his reported beneficial ownership totaled 122,963 shares. All options exercised were fully vested.

Positive

• Acquisition of shares: Reporting person increased direct ownership to 122,963 shares following exercises and purchases.
• Fully vested options exercised: The filing states the exercised options were fully vested, indicating no acceleration or special vesting treatment.
• Transparent tax withholding disclosure: The surrender of 38,090 shares is explicitly described as covering tax obligations, not a sale.

Negative

• Share surrender reduces outstanding shares received: 38,090 shares were surrendered to satisfy tax withholding, lowering net new shares delivered to the reporting person.

Insights

Financial Analyst

TL;DR: Insider exercised vested options and acquired shares, modestly increasing direct stake; transactions appear routine for compensation-related exercises.

The reported activity shows typical exercise and net-settlement mechanics: a large nonqualified option exercise (62,500 options) and a smaller incentive option exercise (16,666 options), with 38,090 shares surrendered solely to cover tax withholding. The exercises were at a $12 strike and the filings state the options were fully vested. Net effect increases direct ownership to 122,963 shares. For investors, this is operational insider activity tied to compensation rather than a market sale or material change in control.

Corporate Governance Expert

TL;DR: Transactions comply with Section 16 reporting; tax-withholding surrender is disclosed and not a disposition by sale.

The Form 4 discloses timely reporting of option exercises and share acquisitions by an officer (EVP, CRO, CCO). The filing explicitly notes surrendered shares were for tax withholding and not a sale, which is important for governance transparency. All options were fully vested and dates are provided, supporting proper disclosure practices under Section 16 obligations.

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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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^*

Deitzel Edward

(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, CRO, CCO MIAX Exchanges

3. Date of Earliest Transaction (Month/Day/Year)
09/09/2025

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	09/09/2025		M		62,500	A	$12	144,387	D
Common Stock	09/09/2025		F		38,090(1)	D	$37.3	106,297	D
Common Stock	09/11/2025		M		16,666	A	$12	122,963	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
Nonqualified Stock Option (Right to Buy)	$12	09/09/2025		M			62,500	(2)	09/17/2025	Common Stock	62,500	$0	0	D
Incentive Stock Option (Right to Buy)	$12	09/10/2025		M			16,666	(2)	08/02/2026	Common Stock	16,666	$0	0	D

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 options exercised and does not represent a sale by the reporting person

2. The options are fully vested.

Remarks:

	/s/Alessandra Maria Corona Henriques, Attorney-in-Fact	09/11/2025
	** 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 MIAX insider Edward Deitzel do on 09/09/2025 and 09/11/2025?

On 09/09/2025 he exercised 62,500 nonqualified options at $12 and surrendered 38,090 shares for tax withholding; on 09/11/2025 he acquired 16,666 shares at $12.

How many shares does Edward Deitzel beneficially own after these Form 4 transactions?

The Form 4 reports 122,963 shares beneficially owned by the reporting person following the reported transactions.

Were the exercised options vested when Edward Deitzel exercised them?

Yes. The filing states the options exercised were fully vested.

Did Edward Deitzel sell shares as part of these transactions?

No. The filing clarifies that the 38,090 surrendered shares were used to satisfy tax withholding and do not represent a sale by the reporting person.

What were the exercise prices for the options reported on the Form 4?

Both the nonqualified and incentive stock options exercised had a $12 exercise price.