Miami International Holdings GC sells 44,445 shares

Rhea-AI Filing Summary

MIAMI INTERNATIONAL HOLDINGS, INC. executive Barbara J. Comly, EVP, GC & Corporate Secretary, exercised 44,445 nonqualified stock options into common stock at an exercise price of $12.00 per share on August 4, 2026, and sold the resulting 44,445 common shares at a $45.69 weighted average price, with individual trade prices ranging from $45.09 to $46.78, in a sale in open market or private transactions. Following the exercise, she reported 88,889 nonqualified stock options remaining, which are fully vested and expire on May 28, 2028. These trades were effected pursuant to a previously established Rule 10b5-1 trading plan adopted on December 18, 2025.

Insider Trade Summary 10b5-1

Exercise and Sale: 44,445 shares ($1.50M approx. pre-tax spread)

Exercise and Sale 3 txns

Insider Comly Barbara J.

Role EVP, GC & Corporate Secretary

Sold 44,445 shs ($2.03M)

Approx. gross sale proceeds $2.03M

Approx. exercise cost $533K

Approx. pre-tax spread $1.50M

Type	Security	Shares	Price	Value
Exercise	Nonqualified Stock Option (Right to Buy) F1, F3	44,445	$0.00	$0.00
Exercise	Common Stock F1	44,445	$12.00	$533K
Sale	Common Stock F1, F2	44,445	$45.69	$2.03M

Holdings After Transaction: Nonqualified Stock Option (Right to Buy) — 88,889 contracts (Direct); Common Stock — 882,984 shares (Direct)

Footnotes (3)

1. F1. This transaction was effected pursuant to a previously established Rule 10b5-1 Plan adopted by the Reporting Person on December 18, 2025.
2. F2. This transaction was executed in multiple trades throughout the day at prices ranging from $45.09 to $46.78. The price reported above reflects the weighted average sales 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. F3. The options are fully vested.

Key Figures

Options exercised: 44,445 shares Option exercise price: $12.00 per share Shares sold: 44,445 shares +5 more

8 metrics

Options exercised 44,445 shares Nonqualified stock options exercised into common stock on August 4, 2026

Option exercise price $12.00 per share Exercise price of nonqualified stock options converted into common stock

Shares sold 44,445 shares Common stock sold following option exercise on August 4, 2026

Weighted average sale price $45.69 per share Weighted average price for 44,445 MIAX shares sold

Sale price range $45.09–$46.78 per share Multiple trades throughout August 4, 2026

Remaining options 88,889 options Nonqualified stock options reported remaining after the exercise

Option expiration date May 28, 2028 Expiration date of the reported nonqualified stock options

Rule 10b5-1 plan adoption December 18, 2025 Date Comly adopted the trading plan governing these transactions

Key Terms

Rule 10b5-1 Plan, Nonqualified Stock Option, weighted average sales price, derivative security

4 terms

Rule 10b5-1 Plan regulatory

"transaction was effected pursuant to a previously established Rule 10b5-1 Plan"

A Rule 10b5-1 plan is a prearranged, written schedule that lets corporate insiders buy or sell company stock at set times or amounts, even if they later learn material nonpublic information. Think of it like setting an automatic thermostat for trades: it creates a clear record that trades were planned in advance, reducing the risk of insider-trading accusations and helping investors trust that insider transactions are routine rather than based on secret information.

Nonqualified Stock Option financial

"security_title: Nonqualified Stock Option (Right to Buy)"

A nonqualified stock option (NQSO) is a company grant that gives an individual the right to buy shares at a set price but does not meet special tax rules for incentive stock options; when exercised the difference between the market price and the exercise price is treated as ordinary income for the recipient and as a tax-deductible expense for the company. It matters to investors because NQSOs affect an employee’s after-tax proceeds, the company’s reported expenses, and potential share dilution—think of it like a cash bonus that converts into stock but is taxed as regular pay when you take it.

weighted average sales price financial

"price reported above reflects the weighted average sales price"

derivative security financial

"transaction code description: Exercise or conversion of derivative security"

A derivative security is a financial contract whose value comes from the price or performance of something else, such as a stock, bond, commodity, or market index. For investors it acts like an insurance policy or a wager: it can be used to protect against losses, lock in prices, or amplify gains and losses, so it can change a portfolio’s risk and potential return without owning the underlying asset directly.

FAQ

AI-generated questions and answers. How Rhea-AI works. Not financial advice.

What insider transactions did MIAX executive Barbara J. Comly report?

Barbara J. Comly reported exercising 44,445 nonqualified stock options into MIAX common stock at $12.00 per share and selling the resulting 44,445 shares at a weighted average price of $45.69 on August 4, 2026, in open market or private transactions.

How many MIAX shares did Barbara J. Comly sell, and at what price?

She sold 44,445 MIAX common shares at a $45.69 weighted average price. Footnote disclosure states the sale was executed in multiple trades with prices ranging from $45.09 to $46.78 throughout August 4, 2026.

What was the exercise price and structure of Comly's MIAX stock options?

Comly exercised nonqualified stock options to buy 44,445 MIAX shares at an exercise price of $12.00 per share. The options are described as fully vested and, after this exercise, 88,889 options remain outstanding with an expiration date of May 28, 2028.

Were Barbara J. Comly’s MIAX trades made under a Rule 10b5-1 plan?

Yes. A footnote states the transactions were effected pursuant to a previously established Rule 10b5-1 Plan adopted by Barbara J. Comly on December 18, 2025, indicating they followed a pre-arranged trading schedule rather than discretionary timing.

How many MIAX stock options does Comly report remaining after these transactions?

After exercising options for 44,445 shares, Comly reported 88,889 nonqualified stock options remaining. These options are noted as fully vested and carry an expiration date of May 28, 2028, providing ongoing potential to acquire additional MIAX common stock.

What role does Barbara J. Comly hold at MIAX in this Form 4 filing?

Barbara J. Comly is identified as MIAX’s EVP, General Counsel & Corporate Secretary. The Form 4 reflects her position as an officer of the company in connection with exercising nonqualified stock options and selling MIAX common stock on August 4, 2026.

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

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Available on EDGAR 08/06/2026 - 04:10 PM Accepted by SEC EDGAR 08/06/2026 - 04:09 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).

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^*

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)
08/04/2026

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	08/04/2026		M(1)		44,445	A	$12	927,429	D
Common Stock	08/04/2026		S(1)		44,445	D	$45.69(2)	882,984	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	08/04/2026(1)		M			44,445	(3)	05/28/2028	Common Stock	44,445	$0	88,889	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 18, 2025.

2. This transaction was executed in multiple trades throughout the day at prices ranging from $45.09 to $46.78. The price reported above reflects the weighted average sales 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	08/06/2026
	** 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)