SEC Form 3

FORM 3

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES 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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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. Date of Event Requiring Statement (Month/Day/Year) 08/13/2025	3. Issuer Name and Ticker or Trading Symbol MIAMI INTERNATIONAL HOLDINGS, INC. [ MIAX ]
		4. Relationship of Reporting Person(s) to Issuer (Check all applicable) Director 10% Owner X Officer (give title below) Other (specify below) EVP, Strat. Planning & BD	5. 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 Beneficially Owned
1. Title of Security (Instr. 4)	2. Amount of Securities Beneficially Owned (Instr. 4)	3. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	4. Nature of Indirect Beneficial Ownership (Instr. 5)
Common Stock	138,054	D

Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 4)	2. Date Exercisable and Expiration Date (Month/Day/Year)		3. Title and Amount of Securities Underlying Derivative Security (Instr. 4)		4. Conversion or Exercise Price of Derivative Security	5. Ownership Form: Direct (D) or Indirect (I) (Instr. 5)	6. Nature of Indirect Beneficial Ownership (Instr. 5)
	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Series B Preferred Stock	(1)	(1)	Common Stock	500	(1)	D
Nonvoting Common Stock	(2)	(2)	Common Stock	200,475	(2)	D
Incentive Stock Option (Right to Buy)	(3)	08/02/2026	Nonvoting Common Stock	16,666	$12	D
Incentive Stock Option (Right to Buy)	(3)	10/12/2027	Nonvoting Common Stock	8,333	$12	D
Incentive Stock Option (Right to Buy)	(3)	05/17/2028	Nonvoting Common Stock	8,333	$12	D
Incentive Stock Option (Right to Buy)	(3)	07/31/2029	Nonvoting Common Stock	8,333	$12	D
Incentive Stock Option (Right to Buy)	(3)	11/30/2030	Nonvoting Common Stock	6,570	$15.22	D
Incentive Stock Option (Right to Buy)	(3)	09/09/2031	Nonvoting Common Stock	6,195	$16.14	D
Incentive Stock Option (Right to Buy)	(3)	03/09/2032	Nonvoting Common Stock	3,878	$25.78	D
Incentive Stock Option (Right to Buy)	(4)	03/28/2033	Common Stock	5,040	$19.84	D
Incentive Stock Option (Right to Buy)	(5)	06/15/2035	Common Stock	8,928	$22.4	D
Nonqualified Stock Option (Right to Buy)	(6)	08/02/2026	Nonvoting Common Stock	65,334	$12	D
Nonqualified Stock Option (Right to Buy)	(6)	10/12/2027	Nonvoting Common Stock	41,667	$12	D
Nonqualified Stock Option (Right to Buy)	(6)	05/17/2028	Nonvoting Common Stock	91,667	$12	D
Nonqualified Stock Option (Right to Buy)	(6)	07/31/2029	Nonvoting Common Stock	141,667	$12	D
Nonqualified Stock Option (Right to Buy)	(6)	11/30/2030	Nonvoting Common Stock	143,430	$15.22	D
Nonqualified Stock Option (Right to Buy)	(6)	09/09/2031	Nonvoting Common Stock	18,804	$16.14	D
Nonqualified Stock Option (Right to Buy)	(6)	03/09/2032	Nonvoting Common Stock	46,121	$25.78	D
Nonqualified Stock Option (Right to Buy)	(7)	03/28/2033	Common Stock	44,959	$19.84	D
Nonqualified Stock Option (Right to Buy)	(8)	02/15/2034	Common Stock	75,000	$20	D
Nonqualified Stock Option (Right to Buy)	(9)	06/15/2035	Common Stock	41,072	$22.4	D

Explanation of Responses:

1. The shares of Series B Preferred Stock are convertible on a one-for-one basis into shares of common stock commencing on the Company's initial public offering of its common stock ("IPO") effective date, which is August 13, 2025. The Series B Preferred Stock has no expiration date.

2. The shares of nonvoting common stock are convertible on a one-for-one basis into shares of common stock commencing at any time. The nonvoting common stock has no expiration date.

3. The incentive stock options are fully vested. The options were granted initially as the right to buy nonvoting common stock. On the closing date of the IPO, these will convert to the right to buy common stock instead of nonvoting common stock.

4. All the shares subject to this incentive stock option will vest on March 29, 2026 subject to the reporting person's continued service to the Issuer or its subsidiaries through the applicable vesting date.

5. 4,464 of the shares subject to this incentive stock option will vest on each of June 16, 2027 and June 16, 2028, subject to the reporting person's continued service to the Issuer or its subsidiaries through the applicable vesting date.

6. The nonqualified stock options are fully vested. The options were granted initially as the right to buy nonvoting common stock. On the closing date of the IPO, these will convert to the right to buy common stock instead of nonvoting common stock.

7. 33,333 of the shares subject to this nonqualified stock option are vested and the remaining 11,626 will vest on March 29, 2026 subject to the reporting person's continued service to the Issuer or its subsidiaries through the applicable vesting date.

8. 25,000 of the shares subject to this nonqualified stock option are vested, 25,000 will vest on December 31, 2025 and the remaining 25,000 will vest on December 31, 2026, subject to the reporting person's continued service to the Issuer or its subsidiaries through the applicable vesting date.

9. 16,667 of the shares subject to this nonqualified stock option will vest on June 16, 2026, 12,202 will vest on June 16, 2027 and the remaining 12,203 will vest on June 16, 2028 subject to the reporting person's continued service to the Issuer or its subsidiaries through the applicable vesting date.

Remarks:

See Exhibit 24.1 - Power of Attorney

	/s/Alessandra Maria Corona Henriques, Attorney-in-Fact	08/13/2025
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
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