Thomas P. Gallagher - 13 Aug 2025 Form 3 Insider Report for MIAMI INTERNATIONAL HOLDINGS, INC. (MIAX)

Role
Chairman & CEO, Director
Signature
/s/Alessandra Maria Corona Henriques, Attorney-in-Fact
Issuer symbol
MIAX
Transactions as of
13 Aug 2025
Transactions value $
$0
Form type
3
Filing time
13 Aug 2025, 17:08:50 UTC
Next filing
19 Aug 2025
SEC
View on sec.gov

Reporting Owners (1)

Name Relationship Address Signature Signature date CIK
Gallagher Thomas P. Chairman & CEO, Director C/O MIAMI INTERNATIONAL HOLDINGS, INC, 7 ROSZEL ROAD, SUITE 1A, PRINCETON /s/Alessandra Maria Corona Henriques, Attorney-in-Fact 13 Aug 2025 0002080477

Transactions Table

Type Sym Class Transaction Value $ Shares Change % * Price $ Shares After Date Ownership Footnotes
holding MIAX Common Stock 1.9M 13 Aug 2025 By Gallagher Investments, LLC F1

Derivative Securities (e.g., puts, calls, warrants, options, convertible securities)

Type Sym Class Transaction Value $ Shares Change % * Price $ Shares After Date Underlying Class Amount Exercise Price Ownership Footnotes
holding MIAX Series B Preferred Stock 13 Aug 2025 Common Stock 500 By Gallagher Investments, LLC F1, F2
holding MIAX Nonvoting Common Stock 13 Aug 2025 Common Stock 574K Direct F3
holding MIAX Nonvoting Common Stock 13 Aug 2025 Common Stock 135K By Gallagher Investments, LLC F1, F3
holding MIAX Incentive Stock Option (Right to Buy) 13 Aug 2025 Nonvoting Common Stock 25K $12.00 Direct F4
holding MIAX Incentive Stock Option (Right to Buy) 13 Aug 2025 Nonvoting Common Stock 16.7K $12.00 Direct F4
holding MIAX Incentive Stock Option (Right to Buy) 13 Aug 2025 Nonvoting Common Stock 8.33K $12.00 Direct F4
holding MIAX Incentive Stock Option (Right to Buy) 13 Aug 2025 Nonvoting Common Stock 13.1K $15.22 Direct F4
holding MIAX Incentive Stock Option (Right to Buy) 13 Aug 2025 Common Stock 13.4K $22.40 Direct F5
holding MIAX Nonqualified Stock Option (Right to Buy) 13 Aug 2025 Nonvoting Common Stock 350K $12.00 By Gallagher Investments, LLC F1, F6
holding MIAX Nonqualified Stock Option (Right to Buy) 13 Aug 2025 Nonvoting Common Stock 283K $12.00 By Gallagher Investments, LLC F1, F6
holding MIAX Nonqualified Stock Option (Right to Buy) 13 Aug 2025 Nonvoting Common Stock 242K $12.00 By Gallagher Investments, LLC F1, F6
holding MIAX Nonqualified Stock Option (Right to Buy) 13 Aug 2025 Nonvoting Common Stock 287K $15.22 By Gallagher Investments, LLC F1, F6
holding MIAX Nonqualified Stock Option (Right to Buy) 13 Aug 2025 Nonvoting Common Stock 375K $16.14 By Gallagher Investments, LLC F1, F6
holding MIAX Nonqualified Stock Option (Right to Buy) 13 Aug 2025 Common Stock 97.9K $22.40 By Gallagher Investments, LLC F1, F7
* An asterisk sign (*) next to the price indicates that the price is likely invalid.

Explanation of Responses:

Id Content
F1 Mr. Gallagher maintains beneficial ownership, including dispositive and voting control, over Gallagher Investments, LLC.
F2 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.
F3 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.
F4 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.
F5 4,464 of the shares subject to this incentive stock option will vest on each of June 16, 2026, 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.
F6 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.
F7 32,620 of the shares subject to this nonqualified stock option will vest on June 16, 2026, 32,619 will vest on June 16, 2027 and the remaining 32,619 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