STOCK TITAN

MIAMI INTERNATIONAL HOLDINGS (MIAX) CEO exercises 24,999 options into shares

Filing Impact
(Moderate)
Filing Sentiment
(Neutral)
Form Type
4

Rhea-AI Filing Summary

MIAMI INTERNATIONAL HOLDINGS, INC. Chairman & CEO Thomas P. Gallagher exercised incentive stock options to acquire 24,999 shares of Common Stock at $12.00 per share. Following the option exercise, he holds 510,962 Common Stock shares directly. The exercised options were fully vested and no share sales were reported.

Positive

  • None.

Negative

  • None.
Insider Gallagher Thomas P.
Role Chairman & CEO
Type Security Shares Price Value
Exercise Incentive Stock Option (Right to Buy) 24,999 $0.00 --
Exercise Common Stock 24,999 $12.00 $300K
Holdings After Transaction: Incentive Stock Option (Right to Buy) — 0 shares (Direct, null); Common Stock — 510,962 shares (Direct, null)
Footnotes (1)
  1. [object Object]
Options exercised 24,999 shares Incentive Stock Option into Common Stock
Exercise price $12.00 per share Strike price of incentive stock option
Shares held after 510,962 shares Common Stock directly owned after exercise
Option expiration August 2, 2026 Incentive Stock Option expiration date
Derivative positions remaining 0 options (this grant) Incentive Stock Option fully exercised in this filing
Incentive Stock Option financial
"security_title: "Incentive Stock Option (Right to Buy)""
An incentive stock option is a type of employee benefit that gives a worker the right to buy company shares at a fixed price, with special tax advantages if the employee holds the shares for a required period. Think of it as a coupon to buy future shares at today’s price that can result in lower tax on the gain. Investors care because ISOs can dilute share count, align staff incentives with the stock price, and affect company compensation costs and the timing of potential share sales.
Exercise or conversion of derivative security financial
"transaction_code_description: "Exercise or conversion of derivative security""
Common Stock financial
"security_title: "Common Stock""
Common stock represents ownership shares in a company, giving investors a stake in its success and a say in important decisions through voting rights. It is the most common type of stock traded on markets and can provide income through dividends, as well as potential for value growth. For investors, holding common stock means sharing in the company’s profits and risks.
SEC Form 4
FORM 4UNITED 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
or Section 30(h) of the Investment Company Act of 1940
OMB APPROVAL
OMB Number:3235-0287
Estimated average burden
hours per response:0.5
Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).
Check this box to indicate that a transaction was made pursuant to a contract, instruction or written plan for the purchase or sale of equity securities of the issuer that is intended to satisfy the affirmative defense conditions of Rule 10b5-1(c). See Instruction 10.
1. Name and Address of Reporting Person*
Gallagher Thomas P.

(Last)(First)(Middle)
C/O MIAMI INTERNATIONAL HOLDINGS, INC
7 ROSZEL ROAD, SUITE 1A

(Street)
PRINCETON NEW JERSEY 08540

(City)(State)(Zip)

UNITED STATES

(Country)
2. Issuer Name and Ticker or Trading Symbol
MIAMI INTERNATIONAL HOLDINGS, INC. [ MIAX ]
5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)
XDirector10% Owner
XOfficer (give title below)Other (specify below)
Chairman & CEO
2a. Foreign Trading Symbol
3. Date of Earliest Transaction (Month/Day/Year)
05/11/2026
6. Individual or Joint/Group Filing (Check Applicable Line)
XForm filed by One Reporting Person
Form filed by More than One Reporting Person
4. If Amendment, Date of Original Filed (Month/Day/Year)

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3) 2. Transaction Date (Month/Day/Year)2A. Deemed Execution Date, if any (Month/Day/Year)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)
CodeVAmount(A) or (D)Price
Common Stock05/11/2026M24,999A$12510,962D
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 (Month/Day/Year)3A. Deemed Execution Date, if any (Month/Day/Year)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 (Month/Day/Year)7. Title and Amount of Securities Underlying Derivative Security (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: Direct (D) or Indirect (I) (Instr. 4) 11. Nature of Indirect Beneficial Ownership (Instr. 4)
CodeV(A)(D)Date ExercisableExpiration DateTitleAmount or Number of Shares
Incentive Stock Option (Right to Buy)$1205/11/2026M24,999 (1)08/02/2026Common Stock24,999$00D
Explanation of Responses:
1. The options are fully vested.
Remarks:
/s/Alessandra Maria Corona Henriques, Attorney-in-Fact05/13/2026
** Signature of Reporting PersonDate
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.
* Form 4: SEC 1474 (03-26)

FAQ

What insider transaction did MIAX Chairman & CEO Thomas P. Gallagher report?

Thomas P. Gallagher reported exercising incentive stock options to acquire 24,999 MIAX Common Stock shares. The transaction was coded as an option exercise, not an open-market purchase or sale, and reflects conversion of a derivative award into directly held shares.

At what price were Thomas P. Gallagher’s MIAX options exercised?

The options were exercised at a strike price of $12.00 per share. This price reflects the pre-set exercise cost of the incentive stock options, which were fully vested before Gallagher converted them into 24,999 shares of MIAX Common Stock.

How many MIAX shares does Thomas P. Gallagher hold after this Form 4 transaction?

After the reported transactions, Thomas P. Gallagher holds 510,962 MIAX Common Stock shares directly. This total includes the 24,999 shares received from exercising fully vested incentive stock options on the reported transaction date.

Did Thomas P. Gallagher sell any MIAX shares in this Form 4 filing?

No shares were reported as sold in this Form 4. The filing shows only the exercise of 24,999 incentive stock options into Common Stock, with no accompanying sale, tax withholding disposition, or gift transactions on the reported date.

What happened to the MIAX incentive stock options after the exercise?

The incentive stock option covering 24,999 shares was fully exercised, leaving 0 options remaining from that grant. The option had an exercise price of $12.00 per share and an expiration date of August 2, 2026 as disclosed in the filing.