Horizon Kinetics (MIAX) exercises warrants and reports share sale

Rhea-AI Filing Summary

MIAMI INTERNATIONAL HOLDINGS, INC. reported that ten percent owner Horizon Kinetics Asset Management LLC (HKAM) exercised warrants for a total of 112,656 shares of common stock on March 2, 2026. The warrants were exercised on a cashless basis, with the issuer withholding 53,578 shares to cover the exercise price and issuing 59,078 shares to HKAM. The filing also shows HKAM reporting an open-market sale of 53,578 common shares at $40.92 per share, leaving HKAM with 4,619,442 common shares held indirectly. Director Murray Stahl is shown with several fully vested option positions held directly, with updated post‑transaction option balances and no new option exercises disclosed.

SEC Form 4

FORM 4

UNITED 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

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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^*

STAHL MURRAY

(Last) (First) (Middle)

470 PARK AVE S

8TH FLOOR SOUTH

(Street)

NEW YORK NY 10016

(City) (State) (Zip)

2. Issuer Name and Ticker or Trading Symbol
MIAMI INTERNATIONAL HOLDINGS, INC. [ MIAX ]

5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)

X	Director		10% Owner
	Officer (give title below)		Other (specify below)

3. Date of Earliest Transaction (Month/Day/Year)
03/02/2026

4. If Amendment, Date of Original Filed (Month/Day/Year)
03/04/2026

6. Individual or Joint/Group Filing (Check Applicable Line)

	Form filed by One Reporting Person
X	Form filed by More than One Reporting Person

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)
			Code	V	Amount	(A) or (D)	Price
Common Stock	03/02/2026		X(1)		21,290	A	$15	4,581,654	I	Horizon Kinetics Asset Management LLC
Common Stock	03/02/2026		X(1)		91,366	A	$20.5	4,673,020	I	Horizon Kinetics Asset Management LLC
Common Stock	03/02/2026		S(1)		53,578	D	$40.92	4,619,442	I	Horizon Kinetics Asset Management LLC

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)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Warrant (right to buy)	$15	03/02/2026		X			21,290	08/13/2025	04/08/2026	Common Stock	21,290	$0	0	I	Horizon Kinetics Asset Management LLC
Warrant (right to buy)	$20.5	03/02/2026		X			24,878	08/13/2025	11/15/2026	Common Stock	24,878	$0	0	I	Horizon Kinetics Asset Management LLC
Warrant (right to buy)	$20.5	03/02/2026		X			27,561	08/13/2025	02/05/2027	Common Stock	27,561	$0	0	I	Horizon Kinetics Asset Management LLC
Warrant (right to buy)	$20.5	03/02/2026		X			38,927	08/13/2025	10/17/2026	Common Stock	38,927	$0	0	I	Horizon Kinetics Asset Management LLC
Options	$16.14(2)							08/13/2025	07/31/2031	Miami International Holdings Inc	7,500		7,500	D
Options	$25.98(2)							08/13/2025	06/30/2032	Miami International Holdings Inc	10,000		10,000	D
Options	$19.84(2)							08/13/2025	03/26/2033	Miami International Holdings Inc	14,331		14,331	D
Options	$16.14(2)							08/13/2025	05/31/2031	Miami International Holdings Inc	2,500		2,500	D

1. Name and Address of Reporting Person^*

STAHL MURRAY

(Last) (First) (Middle)

470 PARK AVE S

8TH FLOOR SOUTH

(Street)

NEW YORK NY 10016

(City) (State) (Zip)

Relationship of Reporting Person(s) to Issuer

X	Director		10% Owner
	Officer (give title below)		Other (specify below)

1. Name and Address of Reporting Person^*

HORIZON KINETICS ASSET MANAGEMENT LLC

(Last) (First) (Middle)

470 PARK AVE S

8TH FLOOR SOUTH

(Street)

NEW YORK NY 10016

(City) (State) (Zip)

Relationship of Reporting Person(s) to Issuer

	Director	X	10% Owner
	Officer (give title below)		Other (specify below)

Explanation of Responses:

1. This amendment corrects a previous filing that inadvertently included shares that are not subject to reporting and also corrects the share totals. Horizon Kinetics Asset Management LLC (HKAM) exercised warrants to purchase 112,656 shares of common stock at the exercise prices noted. HKAM paid the exercise price on a cashless basis, resulting in the Issuer withholding 53,578 of the warrant shares to pay the exercise price and issuing to HKAM the remaining 59,078 shares.

2. The Options given to Mr. Stahl are fully vested.

	/s/Jay Kesslen, attorney-in-fact	03/06/2026
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
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FAQ

What insider transactions were reported for MIAX in this Form 4/A?

The filing shows Horizon Kinetics Asset Management LLC exercising warrants for 112,656 MIAX shares on a cashless basis and reporting an open-market sale of 53,578 common shares at $40.92 per share, along with updated option holdings for director Murray Stahl.

How many MIAX shares does Horizon Kinetics Asset Management LLC hold after these transactions?

After the reported transactions, Horizon Kinetics Asset Management LLC holds 4,619,442 MIAX common shares indirectly. This reflects the net result of warrant exercises, cashless settlement mechanics, and the reported 53,578-share open-market sale at $40.92 per share.

What does cashless warrant exercise mean in the MIAX Horizon Kinetics filing?

HKAM exercised warrants to buy 112,656 MIAX shares and paid the exercise price in shares rather than cash. The issuer withheld 53,578 warrant shares to cover the cost and issued the remaining 59,078 shares to HKAM as stated in the footnote.

What sale of MIAX stock did Horizon Kinetics report in this Form 4/A?

Horizon Kinetics Asset Management LLC reported selling 53,578 MIAX common shares in an open-market or private transaction at $40.92 per share. This sale is disclosed alongside the warrant exercises and contributes to the updated indirect ownership total.

What is Murray Stahl’s position and what options does he hold in MIAX?

Murray Stahl is a director of MIAMI INTERNATIONAL HOLDINGS, INC. The filing lists several directly held option positions with post-transaction balances of 7,500, 10,000, 14,331, and 2,500 options, and notes that these options are fully vested per the provided footnote.

Why was this MIAX Form 4/A filed as an amendment?

The amendment corrects an earlier report that mistakenly included shares not subject to reporting and incorrect share totals. It clarifies that HKAM exercised warrants for 112,656 shares and explains the cashless exercise structure and resulting share issuance and withholding.