As of September 29, 2026, the three largest insider holders of MIAX are Murray Stahl (Director, 9.26Mn shares), Talal Jassim Al-Bahar (Director, 3.62Mn shares), Thomas P. Gallagher (Chairman Ceo, 2.21Mn shares).
| # | Insider | Position | Direct | Indirect | Total | Share of Insiders | Last Filed |
|---|---|---|---|---|---|---|---|
| 1 | Murray Stahl | Director | 0 | 9,260,484 | 9,260,484 | 56.9% | 06 Mar, 2026 |
| 2 | Thomas P. Gallagher | Chairman Ceo | 786,542 | 1,423,275 | 2,209,817 | 13.6% | 04 Sep, 2026 |
| 3 | Kinetics Asset Management Llc Horizon | TenPercentOwner | 0 | 2,170,898 | 2,170,898 | 13.3% | 21 May, 2026 |
| 4 | Barbara J. Comly | Evp, Gc Corporate Secretary | 839,564 | 0 | 839,564 | 5.2% | 04 Sep, 2026 |
| 5 | Douglas M. Jr Schafer | Evp And Cio | 387,414 | 0 | 387,414 | 2.4% | 04 Sep, 2026 |
| 6 | Shelly Brown | Evp, Chief Strategy Officer | 316,490 | 0 | 316,490 | 1.9% | 17 Sep, 2026 |
| 7 | John Smollen | Evp, New Product Development | 178,212 | 0 | 178,212 | 1.1% | 18 Jun, 2026 |
| 8 | Judson Gray Teekell | Director | 69,251 | 81,000 | 150,251 | 0.9% | 04 Sep, 2026 |
| 9 | Kurt M. Eckert | Director | 149,612 | 0 | 149,612 | 0.9% | 06 Aug, 2026 |
| 10 | Edward Deitzel | Evp, Cro, Cco Miax Exchanges | 119,601 | 0 | 119,601 | 0.7% | 04 Sep, 2026 |
| 11 | Cynthia Schwarzkopf | Director | 88,545 | 0 | 88,545 | 0.5% | 19 Aug, 2026 |
| 12 | Lance Emmons | Evp And Cfo | 86,538 | 0 | 86,538 | 0.5% | 19 Aug, 2026 |
| 13 | Harish Jayabalan | Evp, Ciso And Cro | 78,065 | 0 | 78,065 | 0.5% | 06 Aug, 2026 |
| 14 | Mark F. Raymond | Director | 67,064 | 0 | 67,064 | 0.4% | 17 Jun, 2026 |
| 15 | Paul Stahlin | Director | 42,143 | 0 | 42,143 | 0.3% | 17 Jun, 2026 |
| 16 | Talal Jassim Al-Bahar | Director | 40,891 | 0 | 40,891 | 0.3% | 17 Jun, 2026 |
| 17 | John Beckelman | Director | 15,904 | 0 | 15,904 | 0.1% | 17 Jun, 2026 |
| 18 | Lisa Moore | Director | 12,737 | 0 | 12,737 | 0.1% | 17 Jun, 2026 |
| 19 | Mark I. Massad | Director | 10,737 | 0 | 10,737 | 0.1% | 17 Jun, 2026 |
| 20 | Kenneth W. Lozier | Director | 8,237 | 0 | 8,237 | 0.1% | 17 Jun, 2026 |
| 21 | David A Brown | Director | 7,066 | 0 | 7,066 | 0.0% | 09 Jul, 2026 |
| 22 | Jill E. Sommers | Director | 6,083 | 0 | 6,083 | 0.0% | 17 Jun, 2026 |
| 23 | Eric Sites | Director | 5,684 | 0 | 5,684 | 0.0% | 17 Jun, 2026 |
| 24 | Cees Vermaas | Ceo Of Tiseg | 4,660 | 0 | 4,660 | 0.0% | 18 Jun, 2026 |
| 25 | Jamil Nazarali | Director | 2,500 | 0 | 2,500 | 0.0% | 15 Aug, 2025 |
| 26 | Lee Becker | Director | 2,267 | 0 | 2,267 | 0.0% | 17 Jun, 2026 |
Each row is that insider’s most recently reported position, from Form 4 filings over the last 60 months — which is why this total does not tie to the quarterly series above, where a quarter counts only the insiders who filed in it. Shares held through a fund or institutional portfolio are counted on the institutional ownership page instead.
| Date | Insider | Position | Transaction | Shares | Price | Value | Shares Held After | Ownership |
|---|---|---|---|---|---|---|---|---|
| 16 Sep, 2026 | Shelly Brown | Evp, Chief Strategy Officer | Disposed S | 21,217 | $38.61 | $819.19K | 316,490 | Direct |
| 11 Sep, 2026 | Shelly Brown | Evp, Chief Strategy Officer | Disposed F | 16,283 | $42.54 | $692.68K | 337,707 | Direct |
| 02 Sep, 2026 | Judson Gray Teekell | Director | Disposed S | 5,545 | $41.58 | $230.56K | 81,000 | Indirect |
| 02 Sep, 2026 | Douglas M. Jr Schafer | Evp And Cio | Acquired M | 43,334 | $12.00 | $520.01K | 430,748 | Direct |
| 03 Sep, 2026 | Edward Deitzel | Evp, Cro, Cco Miax Exchanges | Acquired M | 11,000 | $12.00 | $132.00K | 130,601 | Direct |
| 03 Sep, 2026 | Thomas P. Gallagher | Chairman Ceo | Acquired M | 47,000 | $12.00 | $564.00K | 1,470,275 | Indirect |
| 02 Sep, 2026 | Barbara J. Comly | Evp, Gc Corporate Secretary | Acquired M | 44,445 | $12.00 | $533.34K | 884,009 | Direct |
| 02 Sep, 2026 | Judson Gray Teekell | Director | Disposed S | 3,000 | $40.89 | $122.67K | 69,251 | Direct |
| 02 Sep, 2026 | Barbara J. Comly | Evp, Gc Corporate Secretary | Disposed S | 44,445 | $40.49 | $1.80Mn | 839,564 | Direct |
| 02 Sep, 2026 | Douglas M. Jr Schafer | Evp And Cio | Acquired M | 4,666 | $12.00 | $55.99K | 435,414 | Direct |
| 03 Sep, 2026 | Thomas P. Gallagher | Chairman Ceo | Disposed S | 47,000 | $42.43 | $1.99Mn | 1,423,275 | Indirect |
| 03 Sep, 2026 | Edward Deitzel | Evp, Cro, Cco Miax Exchanges | Disposed S | 11,000 | $42.21 | $464.31K | 119,601 | Direct |
| 03 Sep, 2026 | Edward Deitzel | Evp, Cro, Cco Miax Exchanges | Disposed M | 11,000 | $0.00 | $0 | 66,000 | Direct |
| 02 Sep, 2026 | Douglas M. Jr Schafer | Evp And Cio | Disposed S | 48,000 | $40.48 | $1.94Mn | 387,414 | Direct |
| 03 Sep, 2026 | Thomas P. Gallagher | Chairman Ceo | Acquired M | 16,666 | $12.00 | $199.99K | 760,605 | Direct |
| 02 Sep, 2026 | Barbara J. Comly | Evp, Gc Corporate Secretary | Disposed M | 44,445 | $0.00 | $0 | 44,444 | Direct |
| 02 Sep, 2026 | Douglas M. Jr Schafer | Evp And Cio | Disposed M | 43,334 | $0.00 | $0 | 0 | Direct |
| 03 Sep, 2026 | Thomas P. Gallagher | Chairman Ceo | Acquired M | 8,333 | $12.00 | $100.00K | 768,938 | Direct |
| 02 Sep, 2026 | Douglas M. Jr Schafer | Evp And Cio | Disposed M | 4,666 | $0.00 | $0 | 195,334 | Direct |
| 03 Sep, 2026 | Thomas P. Gallagher | Chairman Ceo | Acquired M | 13,140 | $15.22 | $199.99K | 782,078 | Direct |