MIAX · Insider trading · 13F holders · Congress trades
Miami International Holdings, Inc. (MIAX)
Who is buying and selling MIAX: company insiders on SEC Form 4, hedge funds and superinvestors on Form 13F, and members of Congress under the STOCK Act. Every figure links to the filing or page it comes from.
- 13F filers holding
- 19
- Insider buys, 90 days
- $0
- Insider sales, 90 days
- $25.3M
- Congress trades, 12 months
- 1
MIAX at a glance
- Between Aug 1, 2026 and Oct 29, 2026, 10 MIAX insiders filed 19 sales worth $25.3M on SEC Form 4, and no open-market purchases; 19 of the sales were pre-planned under Rule 10b5-1.
- 19 13F filers hold MIAX among their 50 largest positions, worth $426.9M combined. The biggest bets by portfolio weight are Caldwell Investment Management Ltd. (14.6%), Mad River Investors (4.1%) and Horizon Kinetics Asset Management LLC (3.3%). In their latest 13Fs, 4 managers opened a new position and 4 added to one.
- Members of Congress have disclosed 1 MIAX trade since 2026, 1 purchase and 0 sales in the past year; the latest was Gilbert Ray Cisneros, Jr. (D-CA), buying $15K–50K on Mar 20, 2026.
- MIAX last closed at $31.44 on Oct 29, 2026.
MIAX insider trading
Between Aug 1, 2026 and Oct 29, 2026, 10 MIAX insiders filed 19 sales worth $25.3M on SEC Form 4, and no open-market purchases; 19 of the sales were pre-planned under Rule 10b5-1.
| Filed | Insider | Role | Trade | Shares | Price | Value | Form 4 |
|---|---|---|---|---|---|---|---|
| Oct 26, 2026 | Comly Barbara J. | EVP, GC & Corporate Secretary | Sale10b5-1 | 12,306 | $35.04 | $431K | SEC |
| Oct 26, 2026 | Schafer Douglas M. JR | EVP and CIO | Sale10b5-1 | 8,000 | $35.06 | $280K | SEC |
| Oct 6, 2026 | Schafer Douglas M. JR | EVP and CIO | Sale10b5-1 | 40,000 | $33.34 | $1.3M | SEC |
| Sep 17, 2026 | Brown Shelly | EVP, Chief Strategy Officer | Sale10b5-1 | 21,217 | $38.61 | $819K | SEC |
| Sep 4, 2026 | Gallagher Thomas P. | Chairman & CEO, Director | Sale10b5-1 | 47,000 | $42.43 | $2.0M | SEC |
| Sep 4, 2026 | Schafer Douglas M. JR | EVP and CIO | Sale10b5-1 | 48,000 | $40.48 | $1.9M | SEC |
| Sep 4, 2026 | Comly Barbara J. | EVP, GC & Corporate Secretary | Sale10b5-1 | 44,445 | $40.49 | $1.8M | SEC |
| Sep 4, 2026 | Deitzel Edward | EVP, CRO, CCO MIAX Exchanges | Sale10b5-1 | 11,000 | $42.21 | $464K | SEC |
| Sep 4, 2026 | Teekell Judson Gray | Director | Sale10b5-1 | 8,545 | $41.34 | $353K | SEC |
| Aug 20, 2026 | Gallagher Thomas P. | Chairman & CEO, Director | Sale10b5-1 | 149,700 | $41.13 | $6.2M | SEC |
| Aug 19, 2026 | Emmons Lance | EVP and CFO | Sale10b5-1 | 35,000 | $42.83 | $1.5M | SEC |
| Aug 19, 2026 | Schwarzkopf Cynthia | Director | Sale10b5-1 | 5,000 | $42.85 | $214K | SEC |
| Aug 6, 2026 | Gallagher Thomas P. | Chairman & CEO, Director | Sale10b5-1 | 48,334 | $45.69 | $2.2M | SEC |
| Aug 6, 2026 | Schafer Douglas M. JR | EVP and CIO | Sale10b5-1 | 48,000 | $45.71 | $2.2M | SEC |
| Aug 6, 2026 | Comly Barbara J. | EVP, GC & Corporate Secretary | Sale10b5-1 | 44,445 | $45.69 | $2.0M | SEC |
| Aug 6, 2026 | Jayabalan Harish | EVP, CISO and CRO | Sale10b5-1 | 20,000 | $45.90 | $918K | SEC |
| Aug 6, 2026 | Deitzel Edward | EVP, CRO, CCO MIAX Exchanges | Sale10b5-1 | 11,000 | $45.78 | $504K | SEC |
| Aug 6, 2026 | Teekell Judson Gray | Director | Sale10b5-1 | 3,000 | $45.79 | $137K | SEC |
| Aug 6, 2026 | Eckert Kurt M. | Director | Sale10b5-1 | 1,063 | $45.80 | $49K | SEC |
Who owns MIAX? Hedge funds and superinvestors
19 13F filers hold MIAX among their 50 largest positions, worth $426.9M combined. The biggest bets by portfolio weight are Caldwell Investment Management Ltd. (14.6%), Mad River Investors (4.1%) and Horizon Kinetics Asset Management LLC (3.3%). In their latest 13Fs, 4 managers opened a new position and 4 added to one.
| Manager | % of portfolio | Value | Shares | Last quarter | 13F |
|---|---|---|---|---|---|
| Horizon Kinetics Asset Management LLCAsset manager | 3.3% | $291.4M | 7,842,173 | +127.2% shares | Q2 2026 |
| Caldwell Investment Management Ltd.Hedge fund | 14.6% | $22.3M | 600,000 | -9.6% shares | Q2 2026 |
| Seven Grand Managers, LLCHedge fund | 0.8% | $20.4M | 550,000 | +0.0% shares | Q2 2026 |
| Ghisallo Capital Management LLCHedge fund | 0.4% | $18.6M | 500,000 | -50.0% shares | Q2 2026 |
| Burkehill Global Management, LPHedge fund | 0.4% | $10.8M | 290,000 | +0.0% shares | Q2 2026 |
| Langdon Equity PartnersHedge fund | 5.9% | $10.5M | 282,500 | New | Q2 2026 |
| Mad River InvestorsWealth manager | 4.1% | $10.0M | 297,157 | +2.8% shares | Q3 2026 |
| North Reef Capital Management LPHedge fund | 0.4% | $9.3M | 251,354 | -75.2% shares | Q2 2026 |
| Philadelphia Financial Management of San Francisco, LLCHedge fund | 2.3% | $8.3M | 223,715 | New | Q2 2026 |
| HMV Wealth Advisors, LLCWealth manager | 1.9% | $5.0M | 147,938 | +7.2% shares | Q3 2026 |
| FJ Capital Management LLCHedge fund | 0.6% | $4.4M | 119,299 | — | Q2 2026 |
| One Charles Private Wealth Services, LLCWealth manager | 1.0% | $4.4M | 118,419 | — | Q2 2026 |
| Bullseye Asset Management LLCInstitutional asset manager | 1.9% | $3.6M | 98,170 | +48.9% shares | Q2 2026 |
| G2 Investment Partners Management LLCHedge fund | 0.6% | $3.2M | 85,000 | — | Q2 2026 |
| Atlas Wealth Partners, LLCWealth manager | 1.6% | $1.4M | 38,530 | +2.2% shares | Q2 2026 |
| Capelight Capital Asset Management LPHedge fund | 0.6% | $1.4M | 40,600 | +35.3% shares | Q3 2026 |
| Goodwin Investment AdvisoryWealth manager | 2.1% | $1.0M | 28,025 | New | Q2 2026 |
| SALT Holding Corp.Investment manager | 0.3% | $564K | 15,173 | +0.0% shares | Q2 2026 |
| Msrh, LLCHedge fund | 0.2% | $280K | 7,200 | New | Q1 2026 |
Each manager counts with its latest 13F (Q3 2026: 3, Q2 2026: 15, Q1 2026: 1). Screen MIAX in the grand portfolio →
MIAX stock trades by members of Congress
Members of Congress have disclosed 1 MIAX trade since 2026, 1 purchase and 0 sales in the past year; the latest was Gilbert Ray Cisneros, Jr. (D-CA), buying $15K–50K on Mar 20, 2026.
| Filed | Member | Trade | Amount | Traded | Since |
|---|---|---|---|---|---|
| Apr 7, 2026 | Gilbert Ray Cisneros, Jr.D-CA · House | Buy | $15K–50K | Mar 20, 2026 | -15.4% |
Analysis mentioning MIAX
Posts from the blog that cover Miami International Holdings, Inc., newest first.
MIAX questions and answers
Are insiders buying MIAX stock?
Between Aug 1, 2026 and Oct 29, 2026, 10 MIAX insiders filed 19 sales worth $25.3M on SEC Form 4, and no open-market purchases; 19 of the sales were pre-planned under Rule 10b5-1.
Which hedge funds own MIAX?
19 13F filers hold MIAX among their 50 largest positions, worth $426.9M combined. The biggest bets by portfolio weight are Caldwell Investment Management Ltd. (14.6%), Mad River Investors (4.1%) and Horizon Kinetics Asset Management LLC (3.3%). In their latest 13Fs, 4 managers opened a new position and 4 added to one.
Has Congress traded MIAX?
Members of Congress have disclosed 1 MIAX trade since 2026, 1 purchase and 0 sales in the past year; the latest was Gilbert Ray Cisneros, Jr. (D-CA), buying $15K–50K on Mar 20, 2026.
Who is the largest holder of MIAX?
Among 13F filers, Horizon Kinetics Asset Management LLC reports the largest MIAX position, $291.4M (7,842,173 shares) in its Q2 2026 13F. The biggest bet by portfolio weight is Caldwell Investment Management Ltd.'s: 14.6% of its portfolio.
Cite or share this
Free to use with a link back. The data updates every filing day.