Form 4: MIAX CEO Gallagher Sells Stock Under 10b5-1 Plan

Thomas P. Gallagher, Chairman & CEO of MIAMI INTERNATIONAL HOLDINGS, INC. (MIAX), reported the sale of 15,771 shares of common stock under a pre-arranged Rule 10b5-1 trading plan.

Summary

• Thomas P. Gallagher, Chairman & CEO of MIAMI INTERNATIONAL HOLDINGS, INC. (MIAX), executed a transaction on May 5, 2026.
• He acquired 15,771 shares of common stock at a price of $12 per share, totaling $189,252.
• Concurrently, he disposed of 15,771 shares of common stock at a weighted average price of $47.92 per share, totaling approximately $755,777.
• These transactions were conducted under a Rule 10b5-1 trading plan established on December 29, 2025.
• Following these transactions, Gallagher beneficially owns 1,723,275 shares of common stock indirectly through Gallagher Investments, LLC.

Sentiment

Score: 4

Explanation: StockSavvy.ai views this as a neutral to slightly negative filing due to the significant sale of stock by a top executive, despite the use of a 10b5-1 plan. While the plan itself is a positive governance practice, the sheer volume of shares sold and the profit realized could be interpreted as a signal by some investors.

Positives

• The transactions were executed under a Rule 10b5-1 plan, indicating pre-planned and potentially less market-sensitive trading activity.
• The CEO's continued indirect beneficial ownership of a significant number of shares (1,723,275) suggests ongoing commitment to the company.

Negatives

• A significant number of shares were sold by a key executive, which could be perceived negatively by the market.
• The sale price of $47.92 per share is substantially higher than the acquisition price of $12 per share for the options exercised, indicating a substantial profit for the executive.

Risks

• While executed under a 10b5-1 plan, the sale of a large number of shares by the CEO could be interpreted as a lack of confidence in future price appreciation by some investors.
• The weighted average sale price ranged from $47.13 to $48.35, indicating a significant disposition of stock at prevailing market rates.

Future Outlook

The filing itself does not contain forward-looking statements or guidance. It reports on past transactions.

Management Comments

• The transaction was effected pursuant to a previously established Rule 10b5-1 Plan adopted by the Reporting Person on December 29, 2025.
• Mr. Gallagher maintains beneficial ownership, including dispositive and voting control, over Gallagher Investments, LLC.
• The price reported reflects the weighted average sale price, and the Reporting Person undertakes to provide full information regarding the number of shares and prices at which the transaction was effected upon request.

Industry Context

StockSavvy.ai notes that Form 4 filings are standard disclosures for insider transactions. The use of a Rule 10b5-1 plan is a common strategy for executives to sell shares in a pre-determined manner, aiming to avoid accusations of insider trading. The significant profit realized on the sale of options is typical for executives who have held vested options for a period.

Corporate Governance

Stakeholder Impact

• Shareholders: May view the sale by the CEO with caution, potentially impacting short-term stock sentiment, although the 10b5-1 plan mitigates concerns about insider trading.
• Employees: May interpret the sale as a signal from leadership, though the pre-planned nature of the transaction is a key factor.
• Management: The transaction is a personal financial decision by the CEO, executed within established corporate governance frameworks.

Next Steps

• Monitor future Form 4 filings from Thomas P. Gallagher and other insiders for any further transactions.
• Observe the market's reaction to this sale and any subsequent trading activity of MIAMI INTERNATIONAL HOLDINGS.

Key Dates

Recommendation

The filing reports a standard insider stock sale under a Rule 10b5-1 plan. While the sale by the CEO could be a short-term sentiment negative, the pre-planned nature and the continued substantial indirect beneficial ownership suggest it's a planned liquidity event rather than a lack of confidence. Without other significant financial or strategic news, a 'hold' recommendation is appropriate, pending further developments.

Keywords

Form 4, SEC Filing, Insider Trading, Stock Sale, Rule 10b5-1, MIAMI INTERNATIONAL HOLDINGS, MIAX, Thomas P. Gallagher, CEO, Chairman, Beneficial Ownership, Stock Options