Form 4: MIAX Director Stahl Acquires Shares, Details Holdings

Murray Stahl, a director of Miami International Holdings, Inc., acquired additional common stock and holds significant derivative securities, primarily through Horizon Kinetics Asset Management LLC.

Summary

• Murray Stahl, a director of Miami International Holdings, Inc. (MIAX), acquired 4 shares of common stock at a price of $41.76 per share on September 26, 2025.
• This transaction was executed pursuant to a Rule 10b5-1(c) trading plan.
• Following the reported transaction, Mr. Stahl indirectly beneficially owns 4,557,923 shares of common stock through Horizon Kinetics Asset Management LLC (HKAM).
• Mr. Stahl directly holds fully vested options for a total of 34,831 shares, with exercise prices ranging from $16.14 to $25.98 and expiration dates between May 2031 and March 2033.
• Horizon Kinetics Asset Management LLC indirectly holds vested and presently exercisable warrants for a total of 112,656 shares, with exercise prices ranging from $15 to $20.5 and expiration dates between November 2026 and February 2027.
• Mr. Stahl serves as Chairman, Chief Executive Officer, and Chief Investment Officer of HKAM and disclaims beneficial ownership over the securities managed by HKAM, except to the extent of his pecuniary interest.

Sentiment

Score: 6

Explanation: The sentiment is slightly positive due to a director's acquisition of common stock, indicating confidence. However, the transaction size is minimal, and the filing primarily details existing beneficial ownership and derivative holdings, which are largely known.

Positives

• A director's acquisition of common stock, even a small amount, can signal continued confidence in the company's future prospects.
• The significant indirect beneficial ownership of 4,557,923 common shares by a director and a 10% owner (Horizon Kinetics Asset Management LLC) aligns management and shareholder interests.

Risks

• Mr. Stahl disclaims beneficial ownership over the securities held by Horizon Kinetics Asset Management LLC, except for his pecuniary interest, which could introduce complexity in assessing his total economic exposure and influence.

Future Outlook

This Form 4 filing reports insider transactions and beneficial ownership, and does not contain any forward-looking statements or guidance regarding the company's future outlook.

Management Comments

• Murray Stahl disclaims beneficial ownership over the securities reported, except to the extent of his pecuniary interest therein, if any.
• The filing of this Form shall not be deemed an admission that Mr. Stahl is the beneficial owner of such securities for purposes of Section 16 or any other purpose.

Industry Context

This filing is an insider transaction report, which provides transparency into the trading activities and beneficial ownership of company directors and significant shareholders. It does not directly relate to broader industry trends or competitive landscape analysis, but rather to individual corporate governance and ownership structures within the financial services sector where Miami International Holdings operates.

Comparison to Industry Standards

• The use of a Rule 10b5-1(c) plan for the common stock acquisition aligns with best practices for insider trading compliance, demonstrating a pre-arranged trading strategy to mitigate concerns about trading on material non-public information.
• The detailed disclosure of direct and indirect holdings, including options and warrants, is standard for SEC Form 4 filings, providing comprehensive transparency into insider ownership.

Corporate Governance

Related Party Transactions

• Murray Stahl, as Chairman, CEO, and CIO of Horizon Kinetics Asset Management LLC (HKAM), has indirect beneficial ownership of 4,557,923 common shares and 112,656 warrants through HKAM-managed funds and accounts. This represents a related party arrangement where Mr. Stahl's leadership role at HKAM influences the beneficial ownership of MIAX securities.

Stakeholder Impact

• Shareholders: The director's purchase, though small, may be viewed as a positive signal of management's confidence. The significant indirect holdings through HKAM reinforce alignment of interests.
• Regulatory Authorities: The filing provides required transparency regarding insider trading activities and beneficial ownership, ensuring compliance with Section 16 of the Securities Exchange Act of 1934.

Key Dates

Recommendation

This Form 4 reports a minor common stock acquisition by a director and details existing significant indirect holdings and derivative securities. While insider buying can be a positive signal, the transaction size is too small to materially alter the investment thesis. The substantial existing beneficial ownership through Horizon Kinetics Asset Management LLC is already factored into market expectations, thus a 'hold' recommendation is appropriate as no new significant catalysts or concerns are presented.

Keywords

MIAX, Miami International Holdings, Murray Stahl, Horizon Kinetics Asset Management, Form 4, Insider Trading, Stock Acquisition, Options, Warrants, Beneficial Ownership, Director, 10% Owner, Rule 10b5-1