MIAX CEO Thomas P. Gallagher Exercises Options and Sells Shares

What Happened
Thomas P. Gallagher, Chairman & CEO of Miami International Holdings, Inc. (MIAX), exercised 48,334 vested stock options at $12.00 per share (total exercise cost $580,008) on August 4, 2026, and on the same day sold those 48,334 common shares in the open market for a weighted average price of $45.69 per share (total proceeds $2,208,380). The net proceeds from the transactions were approximately $1,628,372. The sale was executed pursuant to a previously established Rule 10b5-1 trading plan.

Key Details

• Transaction date: August 4, 2026 (Form 4 filed August 6, 2026 — timely within the usual 2-business-day reporting window).
• Exercise: 48,334 shares @ $12.00 = $580,008 (options were fully vested).
• Open-market sale: 48,334 shares @ weighted avg $45.69 = $2,208,380; trades executed across the day at prices ranging $45.09–$46.78.
• Net cash proceeds (sale minus exercise cost): approx. $1,628,372.
• Shares owned after transaction: not specified in this filing.
• Notable footnotes: transaction was effected under a Rule 10b5-1 plan adopted Dec 29, 2025; Mr. Gallagher has beneficial ownership/control through Gallagher Investments, LLC; the filing shows the derivative/options converted/exercised (derivative disposed with $0 value).
• Transaction codes: M = option exercise/conversion; S = open-market sale.

Context
Because the exercised shares were sold the same day, this was effectively a cashless exercise (exercise followed by immediate sale). The presence of a 10b5-1 plan and the intra-day sale range indicate the trades were pre-arranged and executed over multiple trades; this is a routine structure for executives monetizing vested options and does not by itself indicate management’s view of the company.