Welcome to our dedicated page for MIAMI INTERNATIONAL HOLDINGS SEC filings (Ticker: MIAX), a comprehensive resource for investors and traders seeking official regulatory documents including 10-K annual reports, 10-Q quarterly earnings, 8-K material events, and insider trading forms.
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MIAMI INTERNATIONAL HOLDINGS, INC. executive Edward Deitzel reported an exercise-and-sell transaction in company stock. On June 2, 2026, he exercised 11,000 nonqualified stock options at $12.00 per share and sold 11,000 common shares in open-market trades at a weighted average price of $42.16 per share. The sale was carried out under a previously established Rule 10b5-1 trading plan, indicating it was pre-planned. After these transactions, Deitzel directly holds 116,221 common shares, and the option award has 7,333 options remaining outstanding, which are fully vested and expire on May 17, 2028.
MIAMI INTERNATIONAL HOLDINGS, INC. executive Douglas M. Schafer Jr., EVP and CIO, executed an option exercise-and-sale on Common Stock. On June 2, 2026, he exercised 48,000 Nonqualified Stock Options at $12.00 per share to acquire 48,000 common shares, then sold those 48,000 shares in an open-market transaction at a weighted average price of $42.84 per share. These trades were carried out under a previously established Rule 10b5-1 Plan adopted on December 16, 2025. After the transactions, he directly holds 396,681 common shares and 6,000 Nonqualified Stock Options, which are fully vested and remain exercisable until their stated expiration.
MIAMI INTERNATIONAL HOLDINGS, INC. executive Shelly Brown, EVP and Chief Strategy Officer, reported an exercise-and-sale transaction in company common stock. Brown exercised options to acquire 16,000 shares at $12.00 per share and sold 16,000 shares at a weighted average price of $42.12 per share.
The sale was executed in multiple trades on June 2, 2026 under a previously established Rule 10b5-1 trading plan adopted on December 22, 2025. Following these transactions, Brown directly holds 325,047 shares of MIAX common stock.
MIAMI INTERNATIONAL HOLDINGS, INC. Chairman & CEO Thomas P. Gallagher, through Gallagher Investments, LLC, exercised options for 70,000 shares of common stock at $12.00 per share and sold 70,000 shares at a weighted average of $42.36 on June 2, 2026.
The sales were made in open-market transactions under a previously established Rule 10b5-1 Plan adopted on December 29, 2025. Following these transactions, Gallagher Investments, LLC holds 1,723,275 shares of common stock indirectly controlled by Mr. Gallagher.
Horizon Kinetics Asset Management LLC (HKAM), a more than 10% owner of MIAMI INTERNATIONAL HOLDINGS, INC., reported an internal restructuring of its indirect holdings of common stock. The filing shows a non-cash, in-kind pro rata distribution that reduced HKAM’s pecuniary interest in certain shares.
The change reflects a reduction of 2,455,744 shares that were distributed in-kind without consideration, plus 7,200 shares in an account where HKAM no longer has a pecuniary interest. Following these changes, HKAM reports indirect ownership of 2,170,898 shares in this Form 4 and separately reports beneficial ownership of 7,400,316 shares, or 7.8 percent of the issuer’s outstanding shares, in an amended Schedule 13D.
Miami International Holdings, Inc. disclosed an amended Schedule 13D/A showing that Horizon Kinetics Asset Management LLC and its parent Horizon Kinetics Holding Corp beneficially own 7,400,316 shares of common stock, representing 7.8% of the company as of May 19, 2026.
HKAM holds sole voting and dispositive power over these shares, which are owned by client funds and accounts it manages. The position is held for investment purposes, and HKAM may buy or sell shares over time in the ordinary course of business. On May 19, 2026, HKAM distributed 4,084,261 shares in-kind on a pro rata basis, without consideration, to the beneficial owners of its managed accounts in response to client requests.
MIAMI INTERNATIONAL HOLDINGS director Judson Gray Teekell exercised stock options and had shares withheld for taxes. On May 19, 2026, he exercised options to acquire 22,667 shares of common stock at an exercise price of $12.00 per share.
The company withheld 4,991 shares at a reference price of $54.51 per share to cover the option exercise price and related tax obligations, which the footnote states does not represent a market sale. Following these transactions, Teekell directly holds 74,014 common shares.
Miami International Holdings EVP and CFO Lance Emmons sold 35,000 shares of Common Stock in an open-market transaction at an average price of $56.36 per share. After the sale, he directly holds 84,262 shares. The transaction was executed under a previously established Rule 10b5-1 trading plan adopted on December 17, 2025, indicating it was pre-planned rather than a discretionary trade.
MIAX: A Form 144 filing states proposed sales of Common stock totaling 35,000 shares through J.P. Morgan Securities LLC on 05/15/2026 for NYSE-listed shares. The filing lists two vested RSA entries of 18,384 shares (03/10/2023) and 16,616 shares (03/10/2024).
MIAMI INTERNATIONAL HOLDINGS, INC. Chairman & CEO Thomas P. Gallagher exercised incentive stock options to acquire 24,999 shares of Common Stock at $12.00 per share. Following the option exercise, he holds 510,962 Common Stock shares directly. The exercised options were fully vested and no share sales were reported.