Sec Form 4 Filing - STAHL MURRAY @ MIAMI INTERNATIONAL HOLDINGS, INC. - 2025-09-26

FORM 4 Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

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, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person STAHL MURRAY 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 _____ Officer (give title below) _____ Other (specify below) (Last) (First) (Middle) 470 PARK AVE S, 8TH FLOOR SOUTH 3. Date of Earliest Transaction (MM/DD/YY) 09/26/2025 (Street) NEW YORK, NY10016 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) _____ Form filed by One Reporting Person __ X __ Form filed by More than One Reporting Person (City) (State) (Zip)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned 1.Title of Security (Instr. 3) 2. Transaction Date (MM/DD/YY) 2A. Deemed Execution Date, if any (MM/DD/YY) 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 09/26/2025 P 4 A $ 41.76 4,557,923 ( 1 ) ( 2 ) I Horizon Kinetics Asset Management LLC

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 (MM/DD/YY) 3A. Deemed Execution Date, if any (MM/DD/YY) 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 (MM/DD/YY) 7. Title and Amount of Underlying Securities (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 of Derivative Security: 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 OPTIONS $ 16.14 ( 3 ) 08/13/2025 05/31/2031 Miami International Holdings Inc 2,500 2,500 D OPTIONS $ 16.14 ( 3 ) 08/13/2025 07/31/2031 Miami International Holdings Inc 7,500 7,500 D OPTIONS $ 25.98 ( 3 ) 08/13/2025 06/30/2032 Miami International Holdings Inc 10,000 10,000 D OPTIONS $ 19.84 ( 3 ) 08/13/2025 03/26/2033 Miami International Holdings Inc 14,331 14,331 D Warrants $ 20.5 ( 1 ) ( 4 ) 08/13/2025 11/15/2026 Miami International Holdings Inc 24,878 24,878 I Horizon Kinetics Asset Management LLC Warrants $ 20.5 ( 1 ) ( 4 ) 08/13/2025 02/05/2027 Miami International Holdings Inc 27,561 27,561 I Horizon Kinetics Asset Management LLC Warrants $ 15 ( 1 ) ( 4 ) 08/13/2025 04/08/2026 Miami International Holdings Inc 21,290 21,290 I Horizon Kinetics Asset Management LLC Warrants $ 20.5 ( 1 ) ( 4 ) 08/13/2025 10/17/2026 Miami International Holdings Inc 38,927 38,927 I Horizon Kinetics Asset Management LLC

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other STAHL MURRAY 470 PARK AVE S 8TH FLOOR SOUTH NEW YORK, NY10016 X HORIZON KINETICS ASSET MANAGEMENT LLC 470 PARK AVE S 8TH FLOOR SOUTH NEW YORK, NY10016 X Signatures /s/ Jay Kesslen, attorney-in-fact 09/30/2025 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Murray Stahl serves as Chairman, Chief Executive Officer, and Chief Investment Officer of Horizon Kinetics Asset Management LLC ("HKAM"), which manages funds and accounts (the "Managed Accounts") that hold securities of the Issuer. Mr. Stahl does not exercise investment discretion with respect to the securities of the Issuer that are beneficially owned by the Managed Accounts. Mr. Stahl disclaims beneficial ownership over the securities reported, except to the extent of his pecuniary interest therein, if any. The filing of this Form shall not be deemed an admission that the Mr. Stahl is the beneficial owner of such securities for purposes of Section 16 or any other purpose. ( 2 )Includes 5,000 shares of Series B Preferred Stock that have been converted into Common Stock on a one-for-one basis upon the closing of the Company's initial public offering and which have no expiration date and 14,998 shares of Non-Voting Common Stock that have been converted into shares of Common Stock on a one-for-one basis upon the closing of the Company's IPO and which have no expiration date. ( 3 )The Options given to Mr. Stahl are fully vested. ( 4 )The Warrants are currently vested and presently exercisable until the expiration date show.

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).

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