MIAX Form 4: EVP nets 16,283 shares for tax withholding; holds 311,699

Rhea-AI Filing Summary

Shelly Brown, EVP of Strategic Planning & Business Development at Miami International Holdings, Inc. (MIAX), reported a disposition of 16,283 shares of MIAX common stock on 09/10/2025 at a reported price of $36.81 per share. After the transaction, she beneficially owns 311,699 shares, held directly.

The filing explains these shares were surrendered to the company to satisfy tax withholding in connection with the net settlement of restricted stock awards and explicitly states this was not a sale by the reporting person. The Form 4 was submitted by an attorney-in-fact on behalf of the reporting person.

Positive

• Transaction was a tax-withholding net settlement for restricted stock awards, not an open-market sale
• Reporting clarifies the nature of the disposition, meeting disclosure requirements
• Insider retains substantial direct ownership of 311,699 shares following the transaction

Negative

• Beneficial ownership decreased by 16,283 shares following the net settlement
• Form filed by attorney-in-fact, indicating the reporting person did not sign personally (administrative, not substantive)

Insights

Financial Analyst

TL;DR: Insider reduced share count via tax withholding; no open-market sale indicated.

The reported 16,283-share disposition at $36.81 appears to be a routine net settlement for restricted stock tax obligations rather than an active sale, which typically carries less signaling weight for investors. The post-transaction direct ownership remains 311,699 shares, preserving ongoing insider alignment with shareholder interests. For valuation or liquidity implications, this single administrative transaction is immaterial absent other concurrent insider activity.

Corporate Governance Expert

TL;DR: Transaction is a standard tax-withholding settlement of RSUs, documented via Form 4.

From a governance perspective, the disclosure follows Section 16 requirements by reporting the change and clarifying the nature (net settlement for tax withholding). The use of an attorney-in-fact to file the form is routine. The filing does not flag any unusual insider behavior or potential governance concerns based solely on this transaction.

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).

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^*

Brown Shelly

(Last) (First) (Middle)

C/O MIAMI INTERNATIONAL HOLDINGS, INC.

7 ROSZEL ROAD, SUITE 1A

(Street)

PRINCETON NJ 08540

(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)

	Director		10% Owner
X	Officer (give title below)		Other (specify below)
	EVP, Strat. Planning & BD

3. Date of Earliest Transaction (Month/Day/Year)
09/10/2025

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

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

X	Form filed by One Reporting Person
	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	09/10/2025		F		16,283(1)	D	$36.81	311,699	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

Explanation of Responses:

1. Represents shares that have been surrendered to the Company to satisfy tax withholding and remittance obligations in connection with the net settlement of restricted stock awards and does not represent a sale by the reporting person.

Remarks:

	/s/Alessandra Maria Corona Henriques, Attorney-in-Fact	09/11/2025
	** 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.

FAQ

What did MIAX insider Shelly Brown report on Form 4?

The form reports a disposition of 16,283 shares of MIAX common stock at $36.81 per share, resulting in 311,699 shares beneficially owned directly.

Was the 16,283-share disposition an open-market sale?

No. The filing states the shares were surrendered to the company to satisfy tax withholding for net settlement of restricted stock awards and does not represent a sale by the reporting person.

What is the reporting person’s role at MIAX?

The reporting person, Shelly Brown, is identified as an EVP, Strategic Planning & Business Development and an officer of the issuer.

How was the Form 4 submitted?

The Form 4 was executed and filed by an attorney-in-fact on behalf of the reporting person.

Does this Form 4 indicate material insider selling?

The document characterizes the transaction as a tax withholding settlement, not an active sale; based solely on this filing, it is not presented as material insider selling.