Douglas M. Schafer Jr. - 15 Aug 2025 Form 4 Insider Report for MIAMI INTERNATIONAL HOLDINGS, INC. (MIAX)

Reporting relationship: EVP and CIO
Issuer ticker: MIAX
Reported as of: 15 Aug 2025
Net transaction value: $0
SEC form: 4
Accepted by SEC: 19 Aug 2025, 16:07:54 UTC
Prior SEC filing: 13 Aug 2025
Next SEC filing: 12 Feb 2026
Source filing: View source filing
Reporting owner signature: /s/Alessandra Maria Corona Henriques, Attorney-in-Fact

Key filing fact

Douglas M. Schafer Jr. filed Form 4 for MIAMI INTERNATIONAL HOLDINGS, INC. (MIAX) on 19 Aug 2025.

Key facts

This page summarizes Douglas M. Schafer Jr.'s Form 4 filing for MIAMI INTERNATIONAL HOLDINGS, INC. (MIAX).
18 reported transactions and 16 derivative rows are listed below.
Accepted by SEC: 19 Aug 2025, 16:07.

Change

Previous filing in this sequence was filed on 13 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 0002079445 Primary reporting owner

Schafer Douglas M. JR

Relationship: EVP and CIO
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 %: +0.09%
Price
Shares after: 537,796
Date: 15 Aug 2025
Ownership: Direct
Footnotes: F1

MIAX transaction

Common Stock

Conversion of derivative security

Transaction value
Shares: +387,296
Change %: +257%
Price
Shares after: 537,796
Date: 15 Aug 2025
Ownership: Direct
Footnotes: F2

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: Direct
Underlying class: Common Stock
Underlying amount: 500
Exercise price
Footnotes: F1

MIAX transaction Derivative

Nonvoting Common Stock

Conversion of derivative security

Transaction value: $0
Shares: -387,296
Change %: -100%
Price: $0.000000
Shares after: 0
Date: 15 Aug 2025
Ownership: Direct
Underlying class: Common Stock
Underlying amount: 387,296
Exercise price
Footnotes: F2

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: F3, F4

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: F3, F4

MIAX transaction Derivative

Incentive Stock Option (Right to Buy)

Options Exercise

Transaction value: $0
Shares: -19,710
Change %: -100%
Price: $0.000000
Shares after: 0
Date: 15 Aug 2025
Ownership: Direct
Underlying class: Nonvoting Common Stock
Underlying amount: 19,710
Exercise price: $15.22
Footnotes: F3, F4

MIAX transaction Derivative

Incentive Stock Option (Right to Buy)

Options Exercise

Transaction value: $0
Shares: +19,710
Change %
Price: $0.000000
Shares after: 19,710
Date: 15 Aug 2025
Ownership: Direct
Underlying class: Common Stock
Underlying amount: 19,710
Exercise price: $15.22
Footnotes: F3, F4

MIAX transaction Derivative

Nonqualified Stock Option (Right to Buy)

Options Exercise

Transaction value: $0
Shares: -150,000
Change %: -100%
Price: $0.000000
Shares after: 0
Date: 15 Aug 2025
Ownership: Direct
Underlying class: Nonvoting Common Stock
Underlying amount: 150,000
Exercise price: $12.00
Footnotes: F3, F4

MIAX transaction Derivative

Nonqualified Stock Option (Right to Buy)

Options Exercise

Transaction value: $0
Shares: +150,000
Change %
Price: $0.000000
Shares after: 150,000
Date: 15 Aug 2025
Ownership: Direct
Underlying class: Common Stock
Underlying amount: 150,000
Exercise price: $12.00
Footnotes: F3, F4

MIAX transaction Derivative

Nonqualified Stock Option (Right to Buy)

Options Exercise

Transaction value: $0
Shares: -133,334
Change %: -100%
Price: $0.000000
Shares after: 0
Date: 15 Aug 2025
Ownership: Direct
Underlying class: Nonvoting Common Stock
Underlying amount: 133,334
Exercise price: $12.00
Footnotes: F3, F4

MIAX transaction Derivative

Nonqualified Stock Option (Right to Buy)

Options Exercise

Transaction value: $0
Shares: +133,334
Change %
Price: $0.000000
Shares after: 133,334
Date: 15 Aug 2025
Ownership: Direct
Underlying class: Common Stock
Underlying amount: 133,334
Exercise price: $12.00
Footnotes: F3, F4

MIAX transaction Derivative

Nonqualified Stock Option (Right to Buy)

Options Exercise

Transaction value: $0
Shares: -200,000
Change %: -100%
Price: $0.000000
Shares after: 0
Date: 15 Aug 2025
Ownership: Direct
Underlying class: Nonvoting Common Stock
Underlying amount: 200,000
Exercise price: $12.00
Footnotes: F3, F4

MIAX transaction Derivative

Nonqualified Stock Option (Right to Buy)

Options Exercise

Transaction value: $0
Shares: +200,000
Change %
Price: $0.000000
Shares after: 200,000
Date: 15 Aug 2025
Ownership: Direct
Underlying class: Common Stock
Underlying amount: 200,000
Exercise price: $12.00
Footnotes: F3, F4

MIAX transaction Derivative

Nonqualified Stock Option (Right to Buy)

Options Exercise

Transaction value: $0
Shares: -130,290
Change %: -100%
Price: $0.000000
Shares after: 0
Date: 15 Aug 2025
Ownership: Direct
Underlying class: Nonvoting Common Stock
Underlying amount: 130,290
Exercise price: $15.22
Footnotes: F3, F4

MIAX transaction Derivative

Nonqualified Stock Option (Right to Buy)

Options Exercise

Transaction value: $0
Shares: +130,290
Change %
Price: $0.000000
Shares after: 130,290
Date: 15 Aug 2025
Ownership: Direct
Underlying class: Common Stock
Underlying amount: 130,290
Exercise price: $15.22
Footnotes: F3, F4

MIAX transaction Derivative

Nonqualified Stock Option (Right to Buy)

Options Exercise

Transaction value: $0
Shares: -150,000
Change %: -100%
Price: $0.000000
Shares after: 0
Date: 15 Aug 2025
Ownership: Direct
Underlying class: Nonvoting Common Stock
Underlying amount: 150,000
Exercise price: $16.14
Footnotes: F3, F4

MIAX transaction Derivative

Nonqualified Stock Option (Right to Buy)

Options Exercise

Transaction value: $0
Shares: +150,000
Change %
Price: $0.000000
Shares after: 150,000
Date: 15 Aug 2025
Ownership: Direct
Underlying class: Common Stock
Underlying amount: 150,000
Exercise price: $16.14
Footnotes: F3, F4

^* marks a reported price that did not pass the local price check.

Additional SEC filing notes

Filing notes and footnotes

Explanation of responses 4 footnotes

Footnote F1

Represents 500 shares of Series B Preferred Stock, held jointly with his spouse with right of survivorship, 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

Represents 387,296 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 F3

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 F4

The options are fully vested.