Miami International (MIAX) GC surrenders 43K shares, not a market sale

Rhea-AI Filing Summary

MIAMI INTERNATIONAL HOLDINGS, INC. (MIAX) reported an insider equity-tax event by executive officer Barbara J. Comly (EVP, GC & Corporate Secretary). On 2026-08-18, 43,420 shares of common stock at $42.41 per share were surrendered to the company to satisfy tax withholding on restricted stock awards, leaving her with 839,564 shares held directly; this was not an open-market sale.

Insider Trade Summary

Net Seller: 43,420 shares

Net Sell 1 txn

Insider Comly Barbara J.

Role EVP, GC & Corporate Secretary

Type	Security	Shares	Price	Value
Tax Withholding	Common Stock F1	43,420	$42.41	$1.84M

Holdings After Transaction: Common Stock — 839,564 shares (Direct)

Footnotes (1)

1. F1. 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.

Key Figures

Shares surrendered for tax withholding: 43,420 shares Reference price per share: $42.41 per share Shares held after transaction: 839,564 shares +1 more

4 metrics

Shares surrendered for tax withholding 43,420 shares Common stock surrendered on 2026-08-18 to satisfy tax withholding

Reference price per share $42.41 per share Price reported for the 43,420 surrendered shares

Shares held after transaction 839,564 shares Direct holdings of Barbara J. Comly after the 2026-08-18 event

Code F shares for tax or exercise 43,420 shares Exercise-price-or-tax-liability shares in transaction summary

Key Terms

restricted stock awards, net settlement, tax withholding, Form 4

4 terms

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.

net settlement financial

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

tax withholding financial

"to satisfy tax withholding and remittance obligations"

Tax withholding is the practice of taking a portion of a payment—such as wages, dividends, or sale proceeds—before it reaches the recipient and sending that portion to the tax authority as an advance on the recipient’s eventual tax bill. For investors it matters because withholding reduces immediate cash received and affects after‑tax returns, estimated tax payments, and whether you may owe more or receive a refund when taxes are finally calculated, like having a small automatic savings set aside for your tax bill.

Form 4 regulatory

"MIAX reported for Barbara J. Comly in this Form 4"

Form 4 is a official document that company insiders, such as executives or major shareholders, file with regulators whenever they buy or sell company shares. It provides transparency about how those with inside knowledge are trading, helping investors see if insiders are confident in the company's prospects or may be selling for personal reasons. This information can influence investor decisions by revealing insiders' perspectives on the company's value.

FAQ

What insider transaction did MIAX report for Barbara J. Comly?

MIAX reported that Barbara J. Comly surrendered 43,420 shares of common stock on 2026-08-18 to the company to satisfy tax withholding obligations related to restricted stock awards at a reference price of $42.41 per share; it was not an open-market sale.

Was the MIAX Form 4 transaction a stock sale in the market?

No. The Form 4 states the 43,420 shares were surrendered to the company to satisfy tax withholding and remittance obligations from net settlement of restricted stock awards and "does not represent a sale" by Barbara J. Comly.

How many MIAX shares does Barbara J. Comly hold after this transaction?

After the tax-withholding surrender, Barbara J. Comly holds 839,564 shares of MIAX common stock directly, as reported in the Form 4’s post-transaction holdings field.

What price per share is associated with the MIAX insider tax-withholding event?

The Form 4 reports a transaction price of $42.41 per share for the 43,420 shares surrendered to the company in connection with tax withholding on restricted stock awards.

Was the MIAX insider transaction under a Rule 10b5-1 trading plan?

No. The filing’s Rule 10b5-1 checkbox is not checked, and the footnote only describes shares surrendered for tax withholding on restricted stock awards, with no reference to a trading plan.

AI-generated analysis. How Rhea-AI works. Not financial advice.

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Form 4 Insider Transactions: What Each Field Means →

Available on EDGAR 08/20/2026 - 04:12 PM Accepted by SEC EDGAR 08/20/2026 - 04:11 PM Learn about SEC filing dates

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^*

Comly Barbara J.

(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, GC & Corporate Secretary

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
08/18/2026

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	08/18/2026		F		43,420(1)	D	$42.41	839,564	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	08/20/2026
	** 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)