MIAX (MIAX) EVP Smollen surrenders shares to cover stock award taxes

Rhea-AI Filing Summary

MIAMI INTERNATIONAL HOLDINGS, INC. executive John Smollen reported a routine tax-related share disposition. On this Form 4, he surrendered 362 shares of common stock at $37.50 per share to the company to cover tax withholding tied to restricted stock awards. A footnote clarifies this was not an open-market sale by the reporting person. After this transaction, Smollen directly holds 170,757 shares of MIAX common stock.

Insider Trade Summary

1 transaction reported

Mixed 1 txn

Insider Smollen John

Role EVP, New Product Development

Type	Security	Shares	Price	Value
Tax Withholding	Common Stock	362	$37.50	$14K

Holdings After Transaction: Common Stock — 170,757 shares (Direct)

Footnotes (1)

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. Reflects a correction to a clerical error in the Reporting Person's previous filings as to the amount of securities beneficially owned.

Key Figures

Shares surrendered for taxes: 362 shares Transaction price per share: $37.50 per share Shares held after transaction: 170,757 shares +1 more

4 metrics

Shares surrendered for taxes 362 shares Tax-withholding disposition of common stock

Transaction price per share $37.50 per share Value used for tax-withholding surrender

Shares held after transaction 170,757 shares Direct MIAX common stock holdings after Form 4 event

Tax-withholding transactions in filing 1 transaction, 362 shares Aggregate tax-withholding activity in this Form 4

Key Terms

tax-withholding disposition, restricted stock awards, beneficially owned, Common Stock

4 terms

tax-withholding disposition financial

"transaction_action: "tax-withholding disposition""

A tax-withholding disposition is an event or transaction—such as selling or transferring securities, exercising options, or receiving compensation—that triggers a requirement to hold back part of the payment and remit it to tax authorities. It matters to investors because it reduces the cash they receive immediately and can change the timing and amount of taxable income, like a cashier taking a portion of your sale proceeds to pay taxes before you get the rest.

restricted stock awards financial

"in connection with the net settlement of restricted stock awards"

Restricted stock awards are company shares given to employees or executives that cannot be sold or transferred until certain conditions — like staying with the company for a set time or meeting performance targets — are met, like a gift that is locked in a safe until rules are satisfied. Investors care because these awards tie management’s pay to company performance, can increase the number of shares outstanding when they become tradable (dilution), and may signal expected future selling pressure or commitment to long-term growth.

beneficially owned financial

"correction to a clerical error ... as to the amount of securities beneficially owned"

Beneficially owned describes securities or assets where a person has the economic rights and control—such as the right to receive dividends and to direct voting—even if legal title is held in another name. Think of it like having the keys and using a car that’s registered to someone else: you get the benefits and make decisions. Investors care because beneficial ownership reveals who truly controls value and voting power, affecting corporate decisions and takeover dynamics.

Common Stock financial

"security_title: "Common Stock""

Common stock represents ownership shares in a company, giving investors a stake in its success and a say in important decisions through voting rights. It is the most common type of stock traded on markets and can provide income through dividends, as well as potential for value growth. For investors, holding common stock means sharing in the company’s profits and risks.

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Form 4 Insider Transactions: What Each Field Means →

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
Estimated average burden
hours per response:			0.5

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^*

Smollen John

(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, New Product Development

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
03/30/2026

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	03/30/2026		F		362(1)	D	$37.5	170,757(2)	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.

2. Reflects a correction to a clerical error in the Reporting Person's previous filings as to the amount of securities beneficially owned.

Remarks:

	/s/Alessandra Maria Corona Henriques, Attorney-in-Fact	04/01/2026
	** 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 transaction did MIAX EVP John Smollen report on this Form 4?

John Smollen reported surrendering 362 MIAX common shares to the company. The shares were used to satisfy tax withholding obligations related to restricted stock awards, and were not sold on the open market.

Was the MIAX Form 4 transaction by John Smollen an open-market sale?

No, the transaction was not an open-market sale. A footnote states the 362 shares were surrendered to MIAX solely to cover tax withholding and remittance obligations for restricted stock awards.

How many MIAX shares does John Smollen hold after this Form 4 transaction?

After the tax-withholding disposition, John Smollen directly holds 170,757 MIAX common shares. This post-transaction balance reflects a small adjustment from the 362 shares surrendered back to the company for tax obligations.

What price per share was used in John Smollen’s MIAX tax-withholding transaction?

The transaction used a price of $37.50 per MIAX common share. This value applied to the 362 shares surrendered to the company to satisfy tax withholding requirements tied to restricted stock awards.

Did the MIAX Form 4 for John Smollen include any option exercises or derivative transactions?

No, the filing did not show any option exercises or derivative transactions. The only reported activity was a non-derivative tax-withholding disposition of 362 common shares linked to the net settlement of restricted stock awards.