Latest filingAug 20, 2026Most recent Form 4
MIAX
MIAMI INTERNATIONAL HOLDINGS, INC.
NYSEFinancialsSecurity Brokers, Dealers & Flotation Companies
Insider activity for last month from 08/03 to 09/03. Counts use processed Form 4 rows. Purchase and sale metrics use codes P and S; totals remain unknown when any matching value is missing. Rows without a usable transaction date cannot be assigned to a rolling period and are excluded.
Total buying$00 buys
Total selling$787M3 sells
Net open-market-$787M4 insiders
Open-market mix
Buy vs sell distribution by transaction countInsider activity report
Monthly open-market purchase and sale counts Buys Sells
Transaction codes
By Form 4 transaction code in selected period7transactions
- S · Open-market sells · dominant3 · 43%
- F · Tax withholding2 · 29%
- M · Option exercise2 · 29%
Activity by reported role
A joint filing can contribute to multiple roles11transactions
- Director · dominant3 · 27%
- Chief executive officer2 · 18%
- CHAIR2 · 18%
- EC1 · 9%
- EVP1 · 9%
- GC1 · 9%
- SECY1 · 9%
Distinct insiders active
Reporting-owner CIKs by month · peak Aug 2026 (4)Aug 2026Sep 2026
Reported Holdings After
Separated by insider, security, and ownership typeSchwarzkopf CynthiaCommon Stock · Direct
88,545Aug 17, 2026
Gallagher Thomas P.Common Stock · Indirect · By Gallagher Investments, LLC
1,423,275Aug 19, 2026
Emmons LanceCommon Stock · Direct
86,538Aug 17, 2026
Schwarzkopf CynthiaStock Option (Right to Buy) · Direct
11,916Aug 17, 2026
Comly Barbara J.Common Stock · Direct
839,564Aug 18, 2026
These are reported post-transaction holdings, not company-wide ownership percentages. Securities, indirect vehicles, and amendments are kept separate.
Filing activity heatmap
Each cell is one day · intensity = transactions · buys green, sells redAug 03 → Sep 03
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Top insiders
By absolute net value across the selected period- GP-$12.5M
- CJ-$1.8M
- EL-$1.5M
- SC-$154.3k
Filing detail checks
Secondary metrics for the selected periodFiling-only signals
Deterministic matches in the selected period
MIAX transaction history
Filters apply within this company and selected period by default| Ticker | Insider | Role | Type | Shares | Value | Code | Signals | 90d return | Filed | Trans date |
|---|---|---|---|---|---|---|---|---|---|---|
| MIAX | Gallagher Thomas P. | CHAIRCEO | sale10b5-1 | 149k | -$615M | S | +1.9% | 08/20 | 08/19 | |
| MIAX | Gallagher Thomas P. | CHAIRCEO | withholding10b5-1 | 150k | -$637M | F | +1.9% | 08/20 | 08/18 | |
| MIAX | Comly Barbara J. | EVPGCSECY | withholding | 43.4k | -$184M | F | +1.9% | 08/20 | 08/18 | |
| MIAX | Schwarzkopf Cynthia | DIR | exercise10b5-1 | 5.00k | $0 | M | +3.7% | 08/19 | 08/17 | |
| MIAX | Schwarzkopf Cynthia | DIR | sale10b5-1 | 5.00k | -$21.4M | S | +3.7% | 08/19 | 08/17 | |
| MIAX | Schwarzkopf Cynthia | DIR | exercise10b5-1 | 5.00k | $6.00M | M | +3.7% | 08/19 | 08/17 | |
| MIAX | Emmons Lance | EC | sale10b5-1 | 35.0k | -$149M | S | +3.7% | 08/19 | 08/17 |
MIAMI INTERNATIONAL HOLDINGS, INC. Insider Activity FAQ
SEC Form 4 contextWho recently reported transactions at MIAMI INTERNATIONAL HOLDINGS, INC.?
Gallagher Thomas P., Comly Barbara J., Schwarzkopf Cynthia, Emmons Lance.
When was the latest reported open-market purchase?
No code-P purchase is available for this period.
When was the latest reported open-market sale?
Gallagher Thomas P. reported a sale on Aug 19, 2026 valued at $615M. Read the SEC filing.
What is the recent purchase and sale balance?
Net open-market selling in the selected period was $7,870,461.00. Sales can occur for many non-investment reasons.
Where can I see the original SEC filing?
Every transaction row and latest-activity fact links to its original SEC filing.
What do these Form 4 transaction codes mean?
P and S generally describe open-market or private purchases and sales. A, D, F, M, X, G, J, and V describe awards, issuer dispositions, tax withholding, exercises, gifts, other transactions, and voluntary early reports; review each filing and its footnotes for context.