Thomas P. Gallagher - 15 Aug 2025 Form 4 Insider Report for MIAMI INTERNATIONAL HOLDINGS, INC. (MIAX)

Reporting relationship
Chairman & CEO, Director
Issuer ticker
MIAX
Reported as of
15 Aug 2025
Net transaction value
$0
Source evidence Original filing metadata and source links for verification. 5 source fields
SEC form
4
Accepted by SEC
19 Aug 2025, 16:06:02 UTC
Prior SEC filing
15 Aug 2025
Next SEC filing
28 Aug 2025
Source filing
View source filing
Reporting owner 1 detail
Reporting owner signature
/s/Alessandra Maria Corona Henriques, Attorney-in-Fact

Key filing fact

Thomas P. Gallagher filed Form 4 for MIAMI INTERNATIONAL HOLDINGS, INC. (MIAX) on 19 Aug 2025.

Key facts

  • This page summarizes Thomas P. Gallagher's Form 4 filing for MIAMI INTERNATIONAL HOLDINGS, INC. (MIAX).
  • 24 reported transactions and 21 derivative rows are listed below.
  • Accepted by SEC: 19 Aug 2025, 16:06.

Change

  • Previous filing in this sequence was filed on 15 Aug 2025.
  • Current net transaction value: $0.

Research use

  • This tells you what this filing adds before you inspect full transaction and derivative tables.
  • You can trace every row back to the original SEC filing document.

Evidence

Filed on Form 4

Ownership activity is grounded in SEC Form 4 disclosures.

View source filing

Reporting Owners (1)

CIK 0002080477 Primary reporting owner

Gallagher Thomas P.

Relationship
Chairman & CEO, Director
Address
C/O MIAMI INTERNATIONAL HOLDINGS, INC, 7 ROSZEL ROAD, SUITE 1A, PRINCETON
Signature
/s/Alessandra Maria Corona Henriques, Attorney-in-Fact
Signature date
19 Aug 2025

Reported non-derivative transactions

Shares, units, or other non-derivative securities reported in this filing.

MIAX transaction

Common Stock

Conversion of derivative security

Transaction value
Shares
+500
Change %
+0.02%
Price
Shares after
2,040,494
Date
15 Aug 2025
Ownership
By Gallagher Investments, LLC
Footnotes
F1, F2
MIAX transaction

Common Stock

Conversion of derivative security

Transaction value
Shares
+573,963
Change %
+4783%
Price
Shares after
585,963
Date
15 Aug 2025
Ownership
Direct
Footnotes
F3, F4
MIAX transaction

Common Stock

Conversion of derivative security

Transaction value
Shares
+135,395
Change %
+7.1%
Price
Shares after
2,040,494
Date
15 Aug 2025
Ownership
By Gallagher Investments, LLC
Footnotes
F2, F5

Reported derivative securities

Options, warrants, convertible securities, or similar derivative positions disclosed in the filing.

MIAX transaction Derivative

Series B Preferred Stock

Conversion of derivative security

Transaction value
$0
Shares
-500
Change %
-100%
Price
$0.000000
Shares after
0
Date
15 Aug 2025
Ownership
By Gallagher Investments, LLC
Underlying class
Common Stock
Underlying amount
500
Exercise price
Footnotes
F1, F2
MIAX transaction Derivative

Nonvoting Common Stock

Conversion of derivative security

Transaction value
$0
Shares
-573,963
Change %
-100%
Price
$0.000000
Shares after
0
Date
15 Aug 2025
Ownership
Direct
Underlying class
Common Stock
Underlying amount
573,963
Exercise price
Footnotes
F3
MIAX transaction Derivative

Nonvoting Common Stock

Conversion of derivative security

Transaction value
$0
Shares
-135,395
Change %
-100%
Price
$0.000000
Shares after
0
Date
15 Aug 2025
Ownership
By Gallagher Investments, LLC
Underlying class
Common Stock
Underlying amount
135,395
Exercise price
Footnotes
F2, F5
MIAX transaction Derivative

Incentive Stock Option (Right to Buy)

Options Exercise

Transaction value
$0
Shares
-24,999
Change %
-100%
Price
$0.000000
Shares after
0
Date
15 Aug 2025
Ownership
Direct
Underlying class
Nonvoting Common Stock
Underlying amount
24,999
Exercise price
$12.00
Footnotes
F6, F7
MIAX transaction Derivative

Incentive Stock Option (Right to Buy)

Options Exercise

Transaction value
$0
Shares
+24,999
Change %
Price
$0.000000
Shares after
24,999
Date
15 Aug 2025
Ownership
Direct
Underlying class
Common Stock
Underlying amount
24,999
Exercise price
$12.00
Footnotes
F6, F7
MIAX transaction Derivative

Incentive Stock Option (Right to Buy)

Options Exercise

Transaction value
$0
Shares
-16,666
Change %
-100%
Price
$0.000000
Shares after
0
Date
15 Aug 2025
Ownership
Direct
Underlying class
Nonvoting Common Stock
Underlying amount
16,666
Exercise price
$12.00
Footnotes
F6, F7
MIAX transaction Derivative

Incentive Stock Option (Right to Buy)

Options Exercise

Transaction value
$0
Shares
+16,666
Change %
Price
$0.000000
Shares after
16,666
Date
15 Aug 2025
Ownership
Direct
Underlying class
Common Stock
Underlying amount
16,666
Exercise price
$12.00
Footnotes
F6, F7
MIAX transaction Derivative

Incentive Stock Option (Right to Buy)

Options Exercise

Transaction value
$0
Shares
-8,333
Change %
-100%
Price
$0.000000
Shares after
0
Date
15 Aug 2025
Ownership
Direct
Underlying class
Nonvoting Common Stock
Underlying amount
8,333
Exercise price
$12.00
Footnotes
F6, F7
MIAX transaction Derivative

Incentive Stock Option (Right to Buy)

Options Exercise

Transaction value
$0
Shares
+8,333
Change %
Price
$0.000000
Shares after
8,333
Date
15 Aug 2025
Ownership
Direct
Underlying class
Common Stock
Underlying amount
8,333
Exercise price
$12.00
Footnotes
F6, F7
MIAX transaction Derivative

Incentive Stock Option (Right to Buy)

Options Exercise

Transaction value
$0
Shares
-13,140
Change %
-100%
Price
$0.000000
Shares after
0
Date
15 Aug 2025
Ownership
Direct
Underlying class
Nonvoting Common Stock
Underlying amount
13,140
Exercise price
$15.22
Footnotes
F6, F7
MIAX transaction Derivative

Incentive Stock Option (Right to Buy)

Options Exercise

Transaction value
$0
Shares
+13,140
Change %
Price
$0.000000
Shares after
13,140
Date
15 Aug 2025
Ownership
Direct
Underlying class
Common Stock
Underlying amount
13,140
Exercise price
$15.22
Footnotes
F6, F7
MIAX transaction Derivative

Nonqualified Stock Option (Right to Buy)

Options Exercise

Transaction value
$0
Shares
-350,001
Change %
-100%
Price
$0.000000
Shares after
0
Date
15 Aug 2025
Ownership
By Gallagher Investments, LLC
Underlying class
Nonvoting Common Stock
Underlying amount
350,001
Exercise price
$12.00
Footnotes
F2, F6, F7
MIAX transaction Derivative

Nonqualified Stock Option (Right to Buy)

Options Exercise

Transaction value
$0
Shares
+350,001
Change %
Price
$0.000000
Shares after
350,001
Date
15 Aug 2025
Ownership
By Gallagher Investments, LLC
Underlying class
Common Stock
Underlying amount
350,001
Exercise price
$12.00
Footnotes
F2, F6, F7
MIAX transaction Derivative

Nonqualified Stock Option (Right to Buy)

Options Exercise

Transaction value
$0
Shares
-283,334
Change %
-100%
Price
$0.000000
Shares after
0
Date
15 Aug 2025
Ownership
By Gallagher Investments, LLC
Underlying class
Nonvoting Common Stock
Underlying amount
283,334
Exercise price
$12.00
Footnotes
F2, F6, F7
MIAX transaction Derivative

Nonqualified Stock Option (Right to Buy)

Options Exercise

Transaction value
$0
Shares
+283,334
Change %
Price
$0.000000
Shares after
283,334
Date
15 Aug 2025
Ownership
By Gallagher Investments, LLC
Underlying class
Common Stock
Underlying amount
283,334
Exercise price
$12.00
Footnotes
F2, F6, F7
MIAX transaction Derivative

Nonqualified Stock Option (Right to Buy)

Options Exercise

Transaction value
$0
Shares
-241,667
Change %
-100%
Price
$0.000000
Shares after
0
Date
15 Aug 2025
Ownership
By Gallagher Investments, LLC
Underlying class
Nonvoting Common Stock
Underlying amount
241,667
Exercise price
$12.00
Footnotes
F2, F6, F7
MIAX transaction Derivative

Nonqualified Stock Option (Right to Buy)

Options Exercise

Transaction value
$0
Shares
+241,667
Change %
Price
$0.000000
Shares after
241,667
Date
15 Aug 2025
Ownership
By Gallagher Investments, LLC
Underlying class
Common Stock
Underlying amount
241,667
Exercise price
$12.00
Footnotes
F2, F6, F7
MIAX transaction Derivative

Nonqualified Stock Option (Right to Buy)

Options Exercise

Transaction value
$0
Shares
-286,860
Change %
-100%
Price
$0.000000
Shares after
0
Date
15 Aug 2025
Ownership
By Gallagher Investments, LLC
Underlying class
Nonvoting Common Stock
Underlying amount
286,860
Exercise price
$15.22
Footnotes
F2, F6, F7
MIAX transaction Derivative

Nonqualified Stock Option (Right to Buy)

Options Exercise

Transaction value
$0
Shares
+286,860
Change %
Price
$0.000000
Shares after
286,860
Date
15 Aug 2025
Ownership
By Gallagher Investments, LLC
Underlying class
Common Stock
Underlying amount
286,860
Exercise price
$15.22
Footnotes
F2, F6, F7
MIAX transaction Derivative

Nonqualified Stock Option (Right to Buy)

Options Exercise

Transaction value
$0
Shares
-375,000
Change %
-100%
Price
$0.000000
Shares after
0
Date
15 Aug 2025
Ownership
By Gallagher Investments, LLC
Underlying class
Nonvoting Common Stock
Underlying amount
375,000
Exercise price
$16.14
Footnotes
F2, F6, F7
MIAX transaction Derivative

Nonqualified Stock Option (Right to Buy)

Options Exercise

Transaction value
$0
Shares
+375,000
Change %
Price
$0.000000
Shares after
375,000
Date
15 Aug 2025
Ownership
By Gallagher Investments, LLC
Underlying class
Common Stock
Underlying amount
375,000
Exercise price
$16.14
Footnotes
F2, F6, F7
* marks a reported price that did not pass the local price check.

Additional SEC filing notes

Filing notes and footnotes

Explanation of responses 7 footnotes

Footnote F1

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.

Footnote F2

Mr. Gallagher maintains beneficial ownership, including dispositive and voting control, over Gallagher Investments, LLC

Footnote F3

Represents 573,963 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.

Footnote F4

Includes 12,000 shares of common stock jointly with his spouse with right of survival

Footnote F5

Represents 135,395 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.

Footnote F6

The options were granted initially as the right to buy Nonvoting Common Stock. On the closing date of the IPO, these converted to the right to buy Common Stock instead of Nonvoting Common Stock, for the same price and under the same conditions.

Footnote F7

The options are fully vested.

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