Murray Stahl - 12 Dec 2025 Form 4 Insider Report for MIAMI INTERNATIONAL HOLDINGS, INC. (MIAX)

Reporting relationship
Director
Issuer ticker
MIAX
Reported as of
12 Dec 2025
Net transaction value
+$99,999
Source evidence Original filing metadata and source links for verification. 5 source fields
SEC form
4
Accepted by SEC
15 Dec 2025, 15:53:14 UTC
Prior SEC filing
12 Dec 2025
Next SEC filing
16 Dec 2025
Source filing
View source filing
Reporting owner 1 detail
Reporting owner signature
/s/Jay Kesslen, attorney in fact

Key filing fact

Murray Stahl filed Form 4 for MIAMI INTERNATIONAL HOLDINGS, INC. (MIAX) on 15 Dec 2025.

Key facts

  • This page summarizes Murray Stahl's Form 4 filing for MIAMI INTERNATIONAL HOLDINGS, INC. (MIAX).
  • 1 reported transaction and 8 derivative rows are listed below.
  • Accepted by SEC: 15 Dec 2025, 15:53.

Change

  • Previous filing in this sequence was filed on 12 Dec 2025.
  • Current net transaction value: +$99,999.

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 (2)

CIK 0001207097 Primary reporting owner

STAHL MURRAY

Relationship
Director
Address
470 PARK AVE S, 8TH FLOOR SOUTH, NEW YORK
Signature
/s/Jay Kesslen, attorney in fact
Signature date
15 Dec 2025
CIK 0001056823

HORIZON KINETICS ASSET MANAGEMENT LLC

Relationship
10%+ Owner
Address
470 PARK AVE S, 8TH FLOOR SOUTH, NEW YORK
Signature
/s/Jay Kesslen, attorney in fact
Signature date
15 Dec 2025

Reported non-derivative transactions

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

MIAX transaction

Common Stock

Purchase

Transaction value
$99,999
Shares
+2,439
Change %
+0.05%
Price
$41.00
Shares after
4,560,364
Date
12 Dec 2025
Ownership
Horizon Kinetics Asset Management LLC
Footnotes
F1, F2

Reported derivative securities

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

MIAX holding Derivative

Options

No transaction description listed

Transaction value
Shares
Change %
Price
Shares after
7,500
Date
12 Dec 2025
Ownership
Direct
Underlying class
Miami International Holdings Inc
Underlying amount
7,500
Exercise price
$16.14
Footnotes
F3
MIAX holding Derivative

Options

No transaction description listed

Transaction value
Shares
Change %
Price
Shares after
10,000
Date
12 Dec 2025
Ownership
Direct
Underlying class
Miami International Holdings Inc
Underlying amount
10,000
Exercise price
$25.98
Footnotes
F3
MIAX holding Derivative

Options

No transaction description listed

Transaction value
Shares
Change %
Price
Shares after
14,331
Date
12 Dec 2025
Ownership
Direct
Underlying class
Miami International Holdings Inc
Underlying amount
14,331
Exercise price
$19.84
Footnotes
F3
MIAX holding Derivative

Options

No transaction description listed

Transaction value
Shares
Change %
Price
Shares after
2,500
Date
12 Dec 2025
Ownership
Direct
Underlying class
Miami International Holdings Inc
Underlying amount
2,500
Exercise price
$16.14
Footnotes
F3
MIAX holding Derivative

Warrants

No transaction description listed

Transaction value
Shares
Change %
Price
Shares after
24,878
Date
12 Dec 2025
Ownership
Horizon Kinetics Asset Management LLC
Underlying class
Miami International Holdings Inc
Underlying amount
24,878
Exercise price
$20.50
Footnotes
F1, F4
MIAX holding Derivative

Warrants

No transaction description listed

Transaction value
Shares
Change %
Price
Shares after
27,561
Date
12 Dec 2025
Ownership
Horizon Kinetics Asset Management LLC
Underlying class
Miami International Holdings Inc
Underlying amount
27,561
Exercise price
$20.50
Footnotes
F1, F4
MIAX holding Derivative

Warrants

No transaction description listed

Transaction value
Shares
Change %
Price
Shares after
21,290
Date
12 Dec 2025
Ownership
Horizon Kinetics Asset Management LLC
Underlying class
Miami International Holdings Inc
Underlying amount
21,290
Exercise price
$15.00
Footnotes
F1, F4
MIAX holding Derivative

Warrants

No transaction description listed

Transaction value
Shares
Change %
Price
Shares after
38,927
Date
12 Dec 2025
Ownership
Horizon Kinetics Asset Management LLC
Underlying class
Miami International Holdings Inc
Underlying amount
38,927
Exercise price
$20.50
Footnotes
F1, 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

Murray Stahl serves as Chairman, Chief Executive Officer, and Chief Investment Officer of Horizon Kinetics Asset Management LLC ("HKAM"), which manages funds and accounts (the "Managed Accounts") that hold securities of the Issuer. Mr. Stahl does not exercise investment discretion with respect to the securities of the Issuer that are beneficially owned by the Managed Accounts. Mr. Stahl disclaims beneficial ownership over the securities reported, except to the extent of his pecuniary interest therein, if any. The filing of this Form shall not be deemed an admission that the Mr. Stahl is the beneficial owner of such securities for purposes of Section 16 or any other purpose.

Footnote F2

Includes 5,000 shares of Series B Preferred Stock that have been converted into Common Stock on a one-for-one basis upon the closing of the Company's initial public offering and which have no expiration date and 14,998 shares of Non-Voting 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 given to Mr. Stahl are fully vested.

Footnote F4

The Warrants are currently vested and presently exercisable until the expiration date show.

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