Miami International Holdings, Inc. (MIAX)
NYSE: MIAX · Security Brokers, Dealers & Flotation Companies · Princeton, NJ · filing with the SEC since 2008
Who owns Miami International Holdings, Inc.
As filed with the SECHolders of 5% or more
3
Horizon Kinetics Asset Management LLC holds 7.8% of Common Stock, as its SCHEDULE 13D/A filed May 21, 2026 says.
Directors and officers
26
report now, of 26 people on the record since 2025. Their holdings as a group are not read here.
Institutions as a whole
n/a
The record does not read the share held by managers that file Form 13F, so none is printed and no split of the rest is estimated. What it holds is the 3 named at left.
Holders of 5% or moreshare of the class, as filed
Horizon Kinetics Asset Management LLC
SCHEDULE 13D/A · filed May 21, 2026 · Common Stock · 12.2% in Apr 28, 2026
Blackrock, Inc.
SCHEDULE 13G/A · filed Oct 27, 2026 · Common Stock · 5.1% in Jul 29, 2026
T. Rowe Price Investment Management, Inc.
SCHEDULE 13G · filed Aug 14, 2026 · COMMON STOCK
Thomas P. Gallagher
SCHEDULE 13D/A · filed Aug 28, 2025 · Common Stock, $0.001 par value per share (the "Common Stock") · reported falling below 5%, from 5.1% in Aug 21, 2025
What MIAX reports owning in othersstakes of 5% or more, and other ties
Other ties the annual report names
Privately Held Company
An investee · investee · invested in, named in the 10-K filed Mar 6, 2026
Tiseg
A company bought · acquisition, investee · May 2025 · owns, named in the 10-K filed Mar 6, 2026
21 subsidiaries in 4 countries, from the list filed with the 10-K filed Mar 6, 2026.
Insider tradesForm 4
74sales
3purchases
72sales on a scheduled plan
11people selling
$81.8Msold, in dollars
$700,000bought, in dollars
Open-market trades on Form 4 from Nov 9, 2025 to Nov 9, 2026. A scheduled plan is a selling program set in advance under SEC rule 10b5-1. The trades are listed as filed and do not feed the grade.
By calendar yearSoldBought
2026 runs to Nov 9, 2026. Dollars as filed, summed by the transaction date.
People who traded in the window12 of 27 on the roster
| Person | Role as filed | Sales | Sold | On a plan | Buys | Bought |
|---|---|---|---|---|---|---|
| Gallagher Thomas P. | Chairman & CEO | 12 | $32.3M | 12 | 0 | $0 |
| Schafer Douglas M. Jr | EVP and CIO | 10 | $15.6M | 10 | 0 | $0 |
| Comly Barbara J. | EVP, GC & Corporate Secretary | 10 | $13.2M | 10 | 0 | $0 |
| Brown Shelly | EVP, Chief Strategy Officer | 11 | $5.1M | 11 | 0 | $0 |
| Horizon Kinetics Asset Management LLC | 10% owner | 1 | $5.0M | 0 | 1 | $300,000 |
| Emmons Lance | EVP and CFO | 2 | $3.5M | 2 | 0 | $0 |
| Deitzel Edward | EVP, CRO, CCO MIAX Exchanges | 8 | $2.9M | 8 | 0 | $0 |
| Jayabalan Harish | EVP, CISO and CRO | 4 | $2.6M | 4 | 0 | $0 |
| Stahl Murray | director | 1 | $2.2M | 0 | 3 | $700,000 |
| Eckert Kurt M. | director | 5 | $2.2M | 5 | 0 | $0 |
| Schwarzkopf Cynthia | director | 3 | $1.2M | 3 | 0 | $0 |
| Teekell Judson Gray | director | 8 | $1.0M | 7 | 0 | $0 |