10b5-1 sale: Miami International Holdings (MIAX) director sells 3,000 shares

Rhea-AI Filing Summary

Miami International Holdings, Inc. director Teekell Judson Gray reported selling 3,000 shares of Common Stock on August 4, 2026 at a weighted average price of $45.79 per share. Following this sale, he directly holds 72,251 shares. The transaction, executed in multiple trades between $45.13 and $46.56, was carried out under a previously established Rule 10b5-1 trading plan adopted on December 17, 2025.

Insider Trade Summary 10b5-1

Net Seller: 3,000 shares

Net Sell 1 txn

Insider Teekell Judson Gray

Role Director

Sold 3,000 shs ($137K)

Type	Security	Shares	Price	Value
Sale	Common Stock F1, F2	3,000	$45.79	$137K

Holdings After Transaction: Common Stock — 72,251 shares (Direct)

Footnotes (2)

1. F1. This transaction was effected pursuant to a previously established Rule 10b5-1 Plan adopted by the Reporting Person on December 17, 2025.
2. F2. This transaction was executed in multiple trades throughout the day at prices ranging from $45.13 to $46.56. 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.

Key Figures

Shares sold: 3,000 shares Weighted average sale price: $45.79 per share Sale price range: $45.13–$46.56 per share +2 more

5 metrics

Shares sold 3,000 shares Common Stock sold by director on August 4, 2026

Weighted average sale price $45.79 per share Average price for the 3,000 shares sold on August 4, 2026

Sale price range $45.13–$46.56 per share Range of prices across multiple trades executing the sale

Shares owned after transaction 72,251 shares Director’s direct Common Stock holdings following the sale

10b5-1 plan adoption date December 17, 2025 Date the reporting person adopted the Rule 10b5-1 trading plan

Key Terms

Rule 10b5-1 Plan, weighted average sales price, non-derivative

3 terms

Rule 10b5-1 Plan regulatory

"This 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.

weighted average sales price financial

"The price reported above reflects the weighted average sales price"

non-derivative financial

"transaction_type": "non-derivative" for the Common Stock sale"

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 08/06/2026 - 04:12 PM Accepted by SEC EDGAR 08/06/2026 - 04:10 PM Learn about SEC filing dates

FAQ

What insider transaction did MIAX director Teekell Judson Gray report?

MIAX director Teekell Judson Gray reported a sale of 3,000 shares of Common Stock on August 4, 2026. The shares were sold in multiple trades at prices between $45.13 and $46.56, with a weighted average sales price of $45.79 per share.

At what prices did the MIAX insider sell shares on August 4, 2026?

The MIAX insider’s shares were sold in multiple trades at prices ranging from $45.13 to $46.56. The Form 4 reports a weighted average sales price of $45.79 per share, reflecting the overall average across all trades executed that day.

How many MIAX shares does Teekell Judson Gray hold after the reported sale?

After the reported transaction, Teekell Judson Gray directly holds 72,251 shares of Miami International Holdings, Inc. Common Stock. This post-transaction holding reflects his remaining direct ownership position following the sale of 3,000 shares on August 4, 2026.

Was the MIAX insider stock sale executed under a Rule 10b5-1 trading plan?

Yes. The Form 4 states the transaction was effected under a previously established Rule 10b5-1 Plan. The plan was adopted by the reporting person on December 17, 2025, indicating the trades were pre-arranged under that trading framework.

What type of transaction did the MIAX Form 4 classify for the 3,000-share sale?

The MIAX Form 4 classifies the 3,000-share event as an "S" code transaction, described as a sale in an open market or private transaction. It is reported as a non-derivative transaction involving the company’s Common Stock, with direct ownership after the sale.

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^*

Teekell Judson Gray

(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)

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

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		S(1)		3,000	D	$45.79(2)	72,251	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. This transaction was effected pursuant to a previously established Rule 10b5-1 Plan adopted by the Reporting Person on December 17, 2025.

2. This transaction was executed in multiple trades throughout the day at prices ranging from $45.13 to $46.56. 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.

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)