Were the MIAX share sales by Douglas M. Schafer Jr. pre-planned?

Yes. The Form 4 states the sale was effected under a previously established Rule 10b5-1 Plan adopted on December 16, 2025. Such plans pre-schedule trades, making transaction timing more routine and less discretionary.

MIAX (MIAX) EVP Douglas Schafer sells 48,000 shares via 10b5-1 plan

Q: What did MIAX executive Douglas M. Schafer Jr. report in this Form 4?

Douglas M. Schafer Jr., EVP and CIO of MIAX , reported exercising options for 48,000 shares and selling 48,000 shares of Common Stock. The filing details an exercise-and-sale sequence executed in the open market on May 4, 2026.

Q: How many MIAX shares did Douglas M. Schafer Jr. sell and at what price?

He sold 48,000 MIAX Common Stock shares at a weighted average price of $47.25 per share. Trades occurred across multiple executions between $46.80 and $47.71 , with the average reported in the Form 4.

Q: What stock options did Douglas M. Schafer Jr. exercise in this MIAX filing?

He exercised 48,000 nonqualified stock options with a $12.00 exercise price to acquire an equal number of MIAX Common Stock shares. The footnotes state that these options were fully vested at the time of exercise.

Filing Impact

(Neutral)

Filing Sentiment

(Neutral)

Form Type

Rhea-AI Filing Summary

MIAMI INTERNATIONAL HOLDINGS, INC. executive Douglas M. Schafer Jr., EVP and CIO, reported an exercise-and-sale transaction in company stock. He exercised nonqualified stock options to acquire 48,000 shares of Common Stock at $12.00 per share, then sold 48,000 shares in open-market trades at a weighted average price of $47.25 per share. After these transactions, he directly holds 396,681 shares of Common Stock. The sale was carried out under a previously established Rule 10b5-1 Plan adopted on December 16, 2025.

Insider Trade Summary 10b5-1

Net Seller: 48,000 shares ($2,268,000)

Net Sell 3 txns

Insider Schafer Douglas M. JR

Role EVP and CIO

Sold 48,000 shs ($2.27M)

Type	Security	Shares	Price	Value
Exercise	Nonqualified Stock Option (Right to Buy)	48,000	$0.00	--
Exercise	Common Stock	48,000	$12.00	$576K
Sale	Common Stock	48,000	$47.25	$2.27M

Holdings After Transaction: Nonqualified Stock Option (Right to Buy) — 54,000 shares (Direct, null); Common Stock — 444,681 shares (Direct, null)

Footnotes (1)

This transaction was effected pursuant to a previously established Rule 10b5-1 Plan adopted by the Reporting Person on December 16, 2025. This transaction was executed in multiple trades throughout the day at prices ranging from $46.80 to $47.71. The price reported above reflects the weighted average sale 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. The options are fully vested.

Key Figures

Shares sold: 48,000 shares Weighted average sale price: $47.25 per share Sale price range: $46.80–$47.71 per share +3 more

6 metrics

Shares sold 48,000 shares Open-market sale of Common Stock on May 4, 2026

Weighted average sale price $47.25 per share 48,000 shares of Common Stock sold

Sale price range $46.80–$47.71 per share Prices across multiple trades on sale date

Options exercise price $12.00 per share Nonqualified stock options exercised for 48,000 shares

Shares held after transaction 396,681 shares Direct Common Stock ownership after exercise and sale

Rule 10b5-1 plan adoption date December 16, 2025 Plan governing the reported sale transactions

Key Terms

Rule 10b5-1 Plan, Nonqualified Stock Option (Right to Buy), weighted average sale price, open-market sale

4 terms

Rule 10b5-1 Plan regulatory

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

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 (Right to Buy) financial

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

weighted average sale price financial

"The price reported above reflects the weighted average sale price."

open-market sale financial

"transaction_action: "open-market sale""

An open-market sale is when a shareholder sells existing shares directly on a public exchange to any willing buyer, rather than through a private deal. Think of it like putting goods on a busy market stall where price is set by supply and demand; for investors it matters because such sales increase available supply, can put short-term downward pressure on the stock price, and signal changes in liquidity or investor confidence.

Form 4 Insider Transactions: What Each Field Means →

05/05/2026 - 07:32 AM

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^*

Schafer Douglas M. JR

(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 and CIO

2a. Foreign Trading Symbol

3. Date of Earliest Transaction (Month/Day/Year)
05/04/2026

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)
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	Code	V	Amount	(A) or (D)	Price		6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
Common Stock	05/04/2026		M⁽¹⁾		48,000	A	$12	444,681	D
Common Stock	05/04/2026		S⁽¹⁾		48,000	D	$47.25⁽²⁾	396,681	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)
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)	Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares	8. Price of Derivative Security (Instr. 5)		10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
Nonqualified Stock Option (Right to Buy)	$12	05/04/2026		M⁽¹⁾			48,000	⁽³⁾	08/02/2026	Common Stock	48,000	$0	54,000	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 16, 2025.

2. This transaction was executed in multiple trades throughout the day at prices ranging from $46.80 to $47.71. The price reported above reflects the weighted average sale 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 Henriques Corona, Attorney-in-fact	05/05/2026
	** 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)

Source: View Original Filing on SEC EDGAR

FAQ

What did MIAX executive Douglas M. Schafer Jr. report in this Form 4?

Douglas M. Schafer Jr., EVP and CIO of MIAX, reported exercising options for 48,000 shares and selling 48,000 shares of Common Stock. The filing details an exercise-and-sale sequence executed in the open market on May 4, 2026.

How many MIAX shares did Douglas M. Schafer Jr. sell and at what price?

He sold 48,000 MIAX Common Stock shares at a weighted average price of $47.25 per share. Trades occurred across multiple executions between $46.80 and $47.71, with the average reported in the Form 4.

What stock options did Douglas M. Schafer Jr. exercise in this MIAX filing?

He exercised 48,000 nonqualified stock options with a $12.00 exercise price to acquire an equal number of MIAX Common Stock shares. The footnotes state that these options were fully vested at the time of exercise.

How many MIAX shares does Douglas M. Schafer Jr. hold after the transactions?

Following the reported transactions, Douglas M. Schafer Jr. directly holds 396,681 shares of MIAX Common Stock. This figure reflects his position after exercising options and selling 48,000 shares in the open market.

Over what price range were Douglas M. Schafer Jr.’s MIAX shares sold?

The shares were sold in multiple trades at prices ranging from $46.80 to $47.71 per share. The Form 4 reports a weighted average sale price of $47.25 for the 48,000 shares sold.