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Form 3 MIAMI INTERNATIONAL HOLD For: Apr 24 Filed by: Sites Eric

April 28, 2026 3:17 PM
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 *
Sites Eric
(Last) (First) (Middle)
470 PARK AVE S
8TH FLOOR SOUTH
(Street)
NEW YORK NY 10016
(City) (State) (Zip)
2. Date of Event Requiring Statement (Month/Day/Year)
04/24/2026 		3. Issuer Name and Ticker or Trading Symbol
MIAMI INTERNATIONAL HOLDINGS, INC. [ MIAX ]
4. Relationship of Reporting Person(s) to Issuer
(Check all applicable)
X Director 10% Owner
Officer (give title below) Other (specify below)
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)
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
Nonqualified Stock Option (Right to Buy) (1) 08/01/2021 03/26/2030 Miami International Holdings Inc 7,500 16.14 D (2) (3)
Nonqualified Stock Option (Right to Buy) (1) 07/01/2022 03/26/2030 Miami International Holdings Inc 7,500 25.98 D (2) (3)
Nonqualified Stock Option (Right to Buy) (1) 03/27/2023 03/26/2030 Miami International Holdings Inc 9,554 19.84 D (2) (3)
Nonqualified Stock Option (Right to Buy) (1) 04/01/2024 03/26/2030 Miami International Holdings Inc 9,174 20 D (2) (3)
Explanation of Responses:
1. These options are fully vested.
2. On April 24, 2026, Eric Sites, who serves as a Managing Director of Horizon Kinetics Asset Management LLC (HKAM), was elected to the Board of Directors of the Issuer. Mr. Sites does not exercise investment discretion on behalf of HKAM with respect to the securities of the Issuer.
3. On April 28, 2026, HKAM filed an amendment to its Schedule 13D wherein it reported beneficial ownership of 11,162,809 shares.
/s/Jay Kesslen, attorney-in-fact 04/28/2026
** 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).
** 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.

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