MIAX EVP and CIO sells 48,000 shares under Rule 10b5-1 plan (MIAX)

Rhea-AI Filing Summary

MIAMI INTERNATIONAL HOLDINGS EVP and CIO Douglas M. Schafer Jr. exercised stock options and sold shares in a planned transaction. He exercised 48,000 Nonqualified Stock Options at $12.00 per share, receiving 48,000 shares of common stock. The same day, he sold 48,000 common shares at a weighted average price of $39.74 per share in open‑market trades made under a previously established Rule 10b5‑1 trading plan. After these transactions, he directly owns 396,681 common shares. The options exercised were fully vested, and no remaining derivative positions are shown in this filing.

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

OMB APPROVAL

OMB Number:			3235-0287
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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).

X

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^*

Schafer Douglas M. JR

(Last) (First) (Middle)

C/O MIAMI INTERNATIONAL HOLDINGS, INC.

7 ROSZEL ROAD, SUITE 1A

(Street)

PRINCETON NEW JERSEY 08540

(City) (State) (Zip)

UNITED STATES

(Country)

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

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

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

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
03/17/2026

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

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

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

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	03/17/2026		M		48,000	A	$12	444,681	D
Common Stock	03/17/2026		S(1)		48,000	D	$39.74(2)	396,681	D

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
Nonqualified Stock Option (Right to Buy)	$12	03/17/2026		M			48,000	(3)	08/02/2026	Common Stock	48,000	$0	102,000	D

Explanation of Responses:

1. This transaction was effected pursuant to a previously established Rule 10b5-1 Plan adopted by the reporting person on December 16, 2025.

2. This transaction was executed in multiple trades throughout the day at prices ranging from $39.51 to $39.94. The price reported above reflects the weighted average sale price. The reporting person hereby undertakes to provide upon request to the Securities and Exchange Commission staff, the issuer or a security holder of the issuer, full information regarding the number of shares and prices at which the transaction was effected.

3. The options are fully vested.

Remarks:

	/s/Alessandra Maria Corona Henriques, Attorney-in-Fact	03/18/2026
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.
* Form 4: SEC 1474 (03-26)

FAQ

What insider transactions did MIAX EVP Douglas Schafer report on this Form 4?

Douglas M. Schafer Jr. reported an option exercise and a share sale. He exercised 48,000 Nonqualified Stock Options at $12.00 and sold 48,000 common shares at a weighted average price of $39.74 in open‑market transactions.

How many MIAX shares did Douglas Schafer sell and at what price?

Douglas Schafer sold 48,000 MIAX common shares. The shares were sold in multiple trades on the same day at prices ranging from $39.51 to $39.94, with a reported weighted average sale price of $39.74 per share.

How many MIAX shares does Douglas Schafer hold after these transactions?

After the reported transactions, Douglas Schafer directly holds 396,681 MIAX shares. This figure reflects his position following the exercise of 48,000 options and the same‑day sale of 48,000 common shares in the open market.

Were Douglas Schafer’s MIAX share sales under a Rule 10b5‑1 plan?

Yes, the sale was executed under a pre‑arranged Rule 10b5‑1 plan. The filing states the transaction followed a Rule 10b5‑1 trading plan adopted by Douglas M. Schafer Jr. on December 16, 2025, indicating a pre‑scheduled disposition.

What type of MIAX options did Douglas Schafer exercise and at what strike price?

He exercised Nonqualified Stock Options to acquire MIAX common shares. The filing shows an exercise of 48,000 Nonqualified Stock Options with an exercise price of $12.00 per share, and notes that these options were fully vested at the time.

Does this MIAX Form 4 show any remaining options for Douglas Schafer after the exercise?

The filing does not list any remaining derivative positions after the exercise. One derivative transaction for 48,000 Nonqualified Stock Options is reported, and the derivative summary section is empty following that exercise.