Updated Jul 16, 2026
Gallagher Thomas P. has filed 8 SEC Form 4 filings across 1 company in the last 90 days — active on both sides. Lifetime open-market purchases: $276K. Lifetime open-market sales: $21.94M.

Thomas P. Gallagher is the Chairman and CEO of Miami International Holdings, Inc., a company known for operating regulated financial marketplaces. He has played a significant role in the development and management of the MIAX Exchange, leveraging proprietary technology to enhance trading across various asset classes.
| Role | Chairman & CEO, Director |
|---|---|
| Notability | 50/100 |
| Date | Ticker | Company | Code | Shares | Price | Value |
|---|---|---|---|---|---|---|
| 2026-07-14 | MIAX | MIAMI INTERNATIONAL HOLDINGS, INC. | S — Open-market sale [10b5-1] | 70.0K | $42.52 | $2.98M |
| 2026-07-14 | MIAX | MIAMI INTERNATIONAL HOLDINGS, INC. | M — Option exercise [10b5-1] | 70.0K | $12.00 | $840K |
| 2026-07-07 | MIAX | MIAMI INTERNATIONAL HOLDINGS, INC. | S — Open-market sale | 28.2K | $42.27 | $1.19M |
| 2026-07-07 | MIAX | MIAMI INTERNATIONAL HOLDINGS, INC. | M — Option exercise | 28.2K | $12.00 | $339K |
| 2026-07-07 | MIAX | MIAMI INTERNATIONAL HOLDINGS, INC. | S — Open-market sale | 41.8K | $42.09 | $1.76M |
| 2026-07-07 | MIAX | MIAMI INTERNATIONAL HOLDINGS, INC. | M — Option exercise | 41.8K | $12.00 | $501K |
| 2026-06-18 | MIAX | MIAMI INTERNATIONAL HOLDINGS, INC. | A — Grant or award | 233.0K | $0.00 | |
| 2026-06-04 | MIAX | MIAMI INTERNATIONAL HOLDINGS, INC. | S — Open-market sale | 70.0K | $42.36 | $2.97M |
| 2026-06-04 | MIAX | MIAMI INTERNATIONAL HOLDINGS, INC. | M — Option exercise | 70.0K | $12.00 | $840K |
| 2026-05-13 | MIAX | MIAMI INTERNATIONAL HOLDINGS, INC. | M — Option exercise | 25.0K | $12.00 | $300K |
| 2026-05-07 | MIAX | MIAMI INTERNATIONAL HOLDINGS, INC. | S — Open-market sale | 15.8K | $47.92 | $756K |
| 2026-05-07 | MIAX | MIAMI INTERNATIONAL HOLDINGS, INC. | M — Option exercise | 15.8K | $12.00 | $189K |
| 2026-05-05 | MIAX | MIAMI INTERNATIONAL HOLDINGS, INC. | S — Open-market sale | 54.2K | $47.26 | $2.56M |
| 2026-05-05 | MIAX | MIAMI INTERNATIONAL HOLDINGS, INC. | M — Option exercise | 54.2K | $12.00 | $651K |
| 2026-04-17 | MIAX | MIAMI INTERNATIONAL HOLDINGS, INC. | S — Open-market sale | 49.9K | $43.68 | $2.18M |
| 2026-04-17 | MIAX | MIAMI INTERNATIONAL HOLDINGS, INC. | S — Open-market sale | 104.1K | $43.36 | $4.51M |
| 2026-04-17 | MIAX | MIAMI INTERNATIONAL HOLDINGS, INC. | S — Open-market sale | 70.0K | $43.36 | $3.04M |
| 2026-04-17 | MIAX | MIAMI INTERNATIONAL HOLDINGS, INC. | M — Option exercise | 70.0K | $12.00 | $840K |
| 2026-04-01 | MIAX | MIAMI INTERNATIONAL HOLDINGS, INC. | F — Tax withholding / forfeiture | 20.9K | $37.50 | $783K |
| 2026-02-12 | MIAX | MIAMI INTERNATIONAL HOLDINGS, INC. | F — Tax withholding / forfeiture | 50.1K | $41.33 | $2.07M |
Thomas P. Gallagher is the Chairman and CEO of Miami International Holdings, Inc., a company known for operating regulated financial marketplaces. He has played a significant role in the development and management of the MIAX Exchange, leveraging proprietary technology to enhance trading across various asset classes.…
8 primary Form 4 filings in the last 90 days, covering 1 company.
Recorded transactions: 1 open-market purchases ($276K) and 9 open-market sales ($21.94M) across all tracked filings.
All Form 4 filings, transaction values, and 10b5-1 plan flags are listed on this page and updated in real time as new SEC EDGAR filings are processed.
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