Horizon Kinetics (MIAX) uses cashless exercise for large warrant position

Rhea-AI Filing Summary

MIAMI INTERNATIONAL HOLDINGS, INC. insider activity centers on Horizon Kinetics Asset Management LLC (HKAM), a ten percent owner associated with director Murray Stahl. HKAM exercised warrants to purchase 341,522 shares of common stock at the exercise prices noted.

According to the disclosure, HKAM used a cashless exercise structure, with the issuer withholding 121,054 warrant shares to pay the exercise price and issuing 129,102 shares of common stock to HKAM. After these transactions, HKAM’s indirect common stock holdings stood at 4,689,466 shares. Separately, Mr. Stahl holds fully vested options as reported.

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)

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		X(1)		137,500	A	$20	4,810,520	I	Horizon Kinetics Asset Management LLC
Common Stock	03/02/2026		S(1)		121,054	D	$40.92	4,689,466	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
Warrant (right to buy)	$20	03/02/2026		X			137,500	08/13/2025	08/09/2027	Common Stock	137,500	$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. Horizon Kinetics Asset Management LLC (HKAM) exercised warrants to purchase 341,522 shares of common stock at the exercise prices noted. HKAM paid the exercise price on a cashless basis, resulting in the Issuer withholding 121,054 of the warrant shares to pay the exercise price and issuing to HKAM the remaining 129,102 shares.

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

	/s/Jay Kesslen, attorney-in-fact	03/03/2026
	** 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 did Horizon Kinetics Asset Management LLC do in this MIAX Form 4 filing?

Horizon Kinetics Asset Management LLC exercised warrants for 341,522 MIAX shares using a cashless structure. The issuer withheld some warrant shares for the exercise price and issued new common shares to HKAM, updating its indirect ownership position.

How many MIAX shares were withheld and issued in the cashless warrant exercise?

The issuer withheld 121,054 warrant shares to cover the exercise price and issued 129,102 MIAX common shares to Horizon Kinetics Asset Management LLC. This reflects a non-cash, in-the-money warrant exercise rather than a traditional open-market purchase.

What is Horizon Kinetics Asset Management LLC’s MIAX common stock position after these transactions?

Following the reported transactions, Horizon Kinetics Asset Management LLC indirectly holds 4,689,466 shares of MIAX common stock. This figure reflects the net result of the cashless warrant exercise and related share issuances described in the Form 4 filing.

Did Murray Stahl personally buy or sell MIAX common stock in this Form 4?

The reported MIAX common stock activity is attributed to Horizon Kinetics Asset Management LLC, a ten percent owner. For Murray Stahl, the filing notes that his options are fully vested, but it does not show direct common stock purchases or sales by him.

Was the MIAX warrant exercise by Horizon Kinetics a cash transaction?

No, the warrant exercise was cashless. Horizon Kinetics Asset Management LLC exercised warrants, and the issuer withheld 121,054 warrant shares to pay the exercise price instead of taking cash, then issued 129,102 new common shares to HKAM.