Thomas P. Gallagher sold $6.2M of Miami International Holdings, Inc. (MIAX) stock

Thomas P. Gallagher, Chairman & CEO of Miami International Holdings, Inc. (MIAX), sold 149,700 shares of MIAX stock worth $6.2M, per an SEC Form 4 filed Aug 20, 2026.

The sale was pre-arranged (a 10b5-1 plan or an option exercise), not a fresh decision.

The trade happened on Aug 18, 2026, 2 days before it was made public.

MIAX has moved -9.7% since the trade date, from $41.91 to $37.84 (Sep 21, 2026 close).