Sec Form 4 Filing - Deitzel Edward @ MIAMI INTERNATIONAL HOLDINGS, INC. - 2025-08-15

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 Deitzel Edward 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 (Last) (First) (Middle) C/O MIAMI INTERNATIONAL HOLDINGS, INC., 7 ROSZEL ROAD, SUITE 1A 3. Date of Earliest Transaction (MM/DD/YY) 08/15/2025 (Street) PRINCETON, NJ08540 4. If Amendment, Date Original Filed (MM/DD/YY) 6. Individual or Joint/Group Filing (Check Applicable Line) __ X __ Form filed by One Reporting Person _____ 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 08/15/2025 C 500 ( 1 ) A 81,887 D Common Stock 08/15/2025 C 49,194 ( 2 ) A 81,887 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 (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 Series B Preferred Stock ( 1 ) 08/15/2025 C 500 ( 1 ) ( 1 ) ( 1 ) Common Stock 500 $ 0 0 D Nonvoting Common Stock ( 2 ) 08/15/2025 C 49,194 ( 2 ) ( 2 ) ( 2 ) Common Stock 49,194 $ 0 0 D Incentive Stock Option (Right to Buy) $ 12 ( 3 ) 08/15/2025 M 16,666 ( 3 ) ( 4 ) 08/02/2026 Nonvoting Common Stock 16,666 $ 0 0 D Incentive Stock Option (Right to Buy) $ 12 ( 3 ) 08/15/2025 M 16,666 ( 3 ) ( 4 ) 08/02/2026 Common Stock 16,666 $ 0 16,666 D Incentive Stock Option (Right to Buy) $ 12 ( 3 ) 08/15/2025 M 16,666 ( 3 ) ( 4 ) 05/17/2028 Nonvoting Common Stock 16,666 $ 0 0 D Incentive Stock Option (Right to Buy) $ 12 ( 3 ) 08/15/2025 M 16,666 ( 3 ) ( 4 ) 05/17/2028 Common Stock 16,666 $ 0 16,666 D Incentive Stock Option (Right to Buy) $ 12 ( 3 ) 08/15/2025 M 8,333 ( 3 ) ( 4 ) 07/31/2029 Nonvoting Common Stock 8,333 $ 0 0 D Incentive Stock Option (Right to Buy) $ 12 ( 3 ) 08/15/2025 M 8,333 ( 3 ) ( 4 ) 07/31/2029 Common Stock 8,333 $ 0 8,333 D Incentive Stock Option (Right to Buy) $ 15.22 ( 3 ) 08/15/2025 M 6,570 ( 3 ) ( 4 ) 11/30/2030 Nonvoting Common Stock 6,570 $ 0 0 D Incentive Stock Option (Right to Buy) $ 15.22 ( 3 ) 08/15/2025 M 6,570 ( 3 ) ( 4 ) 11/30/2030 Common Stock 6,570 $ 0 6,570 D Incentive Stock Option (Right to Buy) $ 16.14 ( 3 ) 08/15/2025 M 6,195 ( 3 ) ( 4 ) 09/09/2031 Nonvoting Common Stock 6,195 $ 0 0 D Incentive Stock Option (Right to Buy) $ 16.14 ( 3 ) 08/15/2025 M 6,195 ( 3 ) ( 4 ) 09/09/2031 Common Stock 6,195 $ 0 6,195 D Nonqualified Stock Option (Right to Buy) $ 12 ( 3 ) 08/15/2025 M 62,500 ( 3 ) ( 4 ) 09/17/2025 Series B Preferred Stock 62,500 $ 0 0 D Nonqualified Stock Option (Right to Buy) $ 12 ( 3 ) 08/15/2025 M 62,500 ( 3 ) ( 4 ) 09/17/2025 Common Stock 62,500 $ 0 62,500 D Nonqualified Stock Option (Right to Buy) $ 12 ( 3 ) 08/15/2025 M 8,334 ( 3 ) ( 4 ) 08/02/2026 Nonvoting Common Stock 8,334 $ 0 0 D Nonqualified Stock Option (Right to Buy) $ 12 ( 3 ) 08/15/2025 M 8,334 ( 3 ) ( 4 ) 08/02/2026 Common Stock 8,334 $ 0 8,334 D Nonqualified Stock Option (Right to Buy) $ 12 ( 3 ) 08/15/2025 M 33,334 ( 3 ) ( 4 ) 05/17/2028 Nonvoting Common Stock 33,334 $ 0 0 D Nonqualified Stock Option (Right to Buy) $ 12 ( 3 ) 08/15/2025 M 33,334 ( 3 ) ( 4 ) 05/17/2028 Common Stock 33,334 $ 0 33,334 D Nonqualified Stock Option (Right to Buy) $ 12 ( 3 ) 08/15/2025 M 91,667 ( 3 ) ( 4 ) 07/31/2029 Nonvoting Common Stock 91,667 $ 0 0 D Nonqualified Stock Option (Right to Buy) $ 12 ( 3 ) 08/15/2025 M 91,667 ( 3 ) ( 4 ) 07/31/2029 Common Stock 91,667 $ 0 91,667 D Nonqualified Stock Option (Right to Buy) $ 15.22 ( 3 ) 08/15/2025 M 55,930 ( 3 ) ( 4 ) 11/30/2030 Nonvoting Common Stock 55,930 $ 0 0 D Nonqualified Stock Option (Right to Buy) $ 15.22 ( 3 ) 08/15/2025 M 55,930 ( 3 ) ( 4 ) 11/30/2030 Common Stock 55,930 $ 0 55,930 D Nonqualified Stock Option (Right to Buy) $ 16.14 ( 3 ) 08/15/2025 M 56,304 ( 3 ) ( 4 ) 09/09/2031 Nonvoting Common Stock 56,304 $ 0 0 D Nonqualified Stock Option (Right to Buy) $ 16.14 ( 3 ) 08/15/2025 M 56,304 ( 3 ) ( 4 ) 09/09/2031 Common Stock 56,304 $ 0 56,304 D

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Deitzel Edward C/O MIAMI INTERNATIONAL HOLDINGS, INC. 7 ROSZEL ROAD, SUITE 1A PRINCETON, NJ08540 EVP, CRO, CCO MIAX Exchanges Signatures /s/Alessandra Maria Corona Henriques, Attorney-in-Fact 08/19/2025 Signature of Reporting Person Date

Explanation of Responses:

( 1 )Represents 500 shares of Series B Preferred Stock that have been converted into shares of Common Stock on a one-for-one basis upon the closing of the Company's initial public offering ("IPO") and which have no expiration date. ( 2 )Represents 49,194 shares of Nonvoting 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. Includes 5,000 shares held jointly with his spouse with right of survivorship. ( 3 )The options were granted initially as the right to buy Nonvoting Common Stock or Series B Preferred Stock, as applicable. On the closing date of the IPO, these converted to the right to buy Common Stock instead of Nonvoting Common Stock or Series B Preferred Stock, as applicable, for the same price and under the same conditions. ( 4 )The options are fully vested.

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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