The transaction involved the sale of 48,334 shares for $2.2 million, executed at a weighted average price of $45.69 per share on August 4.
All shares were sold indirectly through Gallagher Investments, LLC, an entity over which the CEO maintains beneficial ownership.
The activity was conducted under a Rule 10b5-1 trading plan, representing routine portfolio management rather than a discretionary change in outlook.
Thomas P. Gallagher, chairman and CEO of Miami International Holdings, Inc. (NYSE:MIAX), reported a sale of 48,334 shares on August 4, according to a SEC Form 4 filing.
| Metric | Value |
|---|---|
| Transaction value | $2.2 million |
| Shares sold (indirectly held) | 48,334 |
| Post-transaction shares (indirectly held) | 1,723,275 |
| Post-transaction value | $78.13 million |
Transaction value based on SEC Form 4 weighted average sale price ($45.69); post-transaction value based on the August 4 market close ($45.34).
| Metric | Value |
|---|---|
| Share Price (as of market close 2026-08-05) | $45.96 |
| Market Capitalization | $4.4 billion |
| Revenue (TTM) | $1.5 billion |
| Net Income (TTM) | $142.3 million |
Miami International Holdings is a mid-cap financial services infrastructure provider with a $4.4 billion market capitalization that operates as a critical marketplace operator in U.S. capital markets. The company's diversified platform architecture across options, equities, and futures segments positions it to capture trading volume across multiple asset classes. MIAX maintains competitive advantages through its technology infrastructure, regulatory approvals across multiple asset classes, and established relationships with market participants seeking alternative execution venues.
Gallagher exercised options struck at $12 and sold the resulting shares near $46, which is the kind of trade a founder-CEO makes to turn long-held paper gains into cash, with a preset plan (in this case) to set the timing. He still controls about 1.7 million shares through his investment vehicle, so his stake is barely dented.
Meanwhile, MIAX just posted record second-quarter net revenue of $141 million, up 35%, as options volume climbed 25% to 11 million contracts a day and margins widened, and it cleared a long-running Nasdaq lawsuit with a settlement it has already paid. Gallagher noted it was "another record quarter" driven by the options business and the new Bloomberg futures suite.
The firm debuted on the public market just about one year ago, and it’s up over 30% since. Now that the litigation that shadowed MIAX is resolved, the question for long-term investors is more about whether a young public company can keep options volume growing once volatility cools, since that surge did much of the heavy lifting this quarter.
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Jonathan Ponciano has no position in any of the stocks mentioned. The Motley Fool has positions in and recommends Miami International. The Motley Fool has a disclosure policy.