Form 4 for MIAX MIAMI INTERNATIONAL HOLDINGS, INC.

Accepted 2026-08-20 16:12:06 ET · period of report 2026-08-18 · accession 0002080477-26-000016 · SEC index · Original document

Summary rows

Aggregated the way they appear in lists: one row per insider, transaction code and security table.

X	Filed	Traded	Ticker	Insider	Title	Type	Price	Qty	Owned	ΔOwn	Value
TI	2026-08-20 16:12	2026-08-18	MIAX	Gallagher Thomas P.	COB, CEO, Dir	F - Tax	$42.41	-150.3K	1.57M	-9%	-$6.37M
TI	2026-08-20 16:12	2026-08-19	MIAX	Gallagher Thomas P.	COB, CEO, Dir	S - Sale	$41.13	-149.7K	1.42M	-10%	-$6.16M

Purchase Sale Sale after option exercise All abbreviations

#	Table	Security	Date	Code	A/D	Shares	Price	Owned after	Own	Exercise / expiry	Underlying	Footnotes
1	Common	Common Stock	2026-08-18	F	D	150,300	$42.41	1,572,975	I By Gallagher Investments, LLC	—	—	(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. (F2) Mr. Gallagher maintains beneficial ownership, including dispositive and voting control, over Gallagher Investments, LLC.
2	Common	Common Stock	2026-08-19	S	D	149,700	$41.13	1,423,275	I By Gallagher Investments, LLC	—	—	(F3) This transaction was effected pursuant to a previously established Rule 10b5-1 Plan adopted by the Reporting Person on December 29, 2025. (F4) This transaction was executed in multiple trades throughout the day at prices ranging from $38.85 to $42.56. 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. (F2) Mr. Gallagher maintains beneficial ownership, including dispositive and voting control, over Gallagher Investments, LLC.