Sec Form 3 Filing - Jayabalan Harish @ MIAMI INTERNATIONAL HOLDINGS, INC. - 2025-08-13

FORM 3 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 Jayabalan Harish 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, CISO and CRO (Last) (First) (Middle) C/O MIAMI INTERNATIONAL HOLDINGS, INC., 7 ROSZEL ROAD, SUITE 1A 3. Date of Earliest Transaction (MM/DD/YY) 08/13/2025 (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 3,943 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 ) ( 1 ) ( 1 ) Common Stock 500 D Nonvoting Common Stock ( 2 ) ( 2 ) ( 2 ) Common Stock 43,442 D Incentive Stock Option (Right to Buy) $ 12 ( 3 ) 09/17/2025 Series B Preferred Stock 21,999 D Incentive Stock Option (Right to Buy) $ 12 ( 3 ) 10/12/2027 Nonvoting Common Stock 16,666 D Incentive Stock Option (Right to Buy) $ 12 ( 3 ) 05/17/2028 Nonvoting Common Stock 8,333 D Incentive Stock Option (Right to Buy) $ 12 ( 3 ) 07/31/2029 Nonvoting Common Stock 8,333 D Incentive Stock Option (Right to Buy) $ 15.22 ( 3 ) 11/30/2030 Nonvoting Common Stock 6,570 D Incentive Stock Option (Right to Buy) $ 16.14 ( 3 ) 09/09/2031 Nonvoting Common Stock 6,195 D Incentive Stock Option (Right to Buy) $ 25.78 ( 3 ) 03/09/2032 Nonvoting Common Stock 3,878 D Incentive Stock Option (Right to Buy) $ 19.84 ( 4 ) 03/28/2033 Common Stock 5,040 D Incentive Stock Option (Right to Buy) $ 20.08 ( 5 ) 06/09/2034 Common Stock 4,980 D Incentive Stock Option (Right to Buy) $ 22.4 ( 6 ) 06/15/2035 Common Stock 4,464 D Nonqualified Stock Option (Right to Buy) $ 12 ( 7 ) 09/17/2025 Series B Preferred Stock 3,001 D Nonqualified Stock Option (Right to Buy) $ 12 ( 7 ) 10/12/2027 Nonvoting Common Stock 20,834 D Nonqualified Stock Option (Right to Buy) $ 12 ( 7 ) 05/17/2028 Nonvoting Common Stock 16,667 D Nonqualified Stock Option (Right to Buy) $ 12 ( 7 ) 07/31/2029 Nonvoting Common Stock 16,667 D Nonqualified Stock Option (Right to Buy) $ 15.22 ( 7 ) 11/30/2030 Nonvoting Common Stock 23,430 D Nonqualified Stock Option (Right to Buy) $ 16.14 ( 7 ) 09/09/2031 Nonvoting Common Stock 26,304 D Nonqualified Stock Option (Right to Buy) $ 25.78 ( 7 ) 03/09/2032 Nonvoting Common Stock 8,621 D Nonqualified Stock Option (Right to Buy) $ 24.7 ( 8 ) 09/30/2032 Common Stock 57,500 D Nonqualified Stock Option (Right to Buy) $ 19.84 ( 9 ) 03/28/2033 Common Stock 19,959 D Nonqualified Stock Option (Right to Buy) $ 20.08 ( 10 ) 06/09/2034 Common Stock 15,020 D Nonqualified Stock Option (Right to Buy) $ 22.4 ( 11 ) 06/15/2035 Common Stock 45,536 D

Reporting Owners Reporting Owner Name / Address Relationships Director 10% Owner Officer Other Jayabalan Harish C/O MIAMI INTERNATIONAL HOLDINGS, INC. 7 ROSZEL ROAD, SUITE 1A PRINCETON, NJ08540 EVP, CISO and CRO Signatures /s/Alessandra Maria Corona Henriques, Attorney-in-Fact 08/13/2025 Signature of Reporting Person Date

Explanation of Responses:

( 1 )The shares of Series B Preferred Stock are held jointly with his spouse with right of survivorship and 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 and 4,500 of those shares are held jointly with his spouse with right of survivorship. 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 or Series B preferred stock, as applicable. On the closing date of the IPO, these will convert to the right to buy common stock instead of nonvoting common stock or Series B preferred stock, as applicable. ( 4 )All the shares subject to this incentive stock option will vest on March 9, 2026 subject to the reporting person's continued service to the Issuer or its subsidiaries through the applicable vesting date. ( 5 )All the shares subject to this incentive stock option will vest on June 10, 2027, subject to the reporting person's continued service to the Issuer or its subsidiaries through the applicable vesting date. ( 6 )All the shares subject to this incentive stock option 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. ( 7 )The nonqualified stock options are fully vested. 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 will convert to the right to buy common stock instead of nonvoting common stock or Series B preferred stock, as applicable. ( 8 )38,334 of the shares subject to this nonqualified stock option are vested and the remaining 19,166 will vest on October 1, 2025 subject to the reporting person's continued service to the Issuer or its subsidiaries through the applicable vesting date. ( 9 )16,666 of the shares subject to this nonqualified stock option are vested and the remaining 3,293 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. ( 10 )6,667 of the shares subject to this nonqualified stock option are vested, 6,666 will vest on June 10, 2026 and the remaining 1,687 will vest on June 10, 2027, subject to the reporting person's continued service to the Issuer or its subsidiaries through the applicable vesting date. ( 11 )16,667 of the shares subject to this nonqualified stock option will vest on June 16, 2026, 16,666 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

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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