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MIAX submitted a Form 144 notice reporting proposed sales of common stock related to an exercise of stock options and to previously issued restricted stock awards. The filing lists 350,001 shares tied to the option exercise dated 04/15/2026 and 104,124 shares from restricted awards dated 12/01/2023.
Horizon Kinetics Asset Management LLC filed Amendment No. 2 to its Schedule 13D on Miami International Holdings, Inc., reporting beneficial ownership of 11,061,399 shares of common stock, representing 12.1% of the outstanding class as of the close of business on April 9, 2026.
HKAM holds these shares in managed funds and accounts for investment purposes and may buy or sell additional shares in the ordinary course of business. The filing also notes that on April 7, 2026, Murray Stahl, who served as Chairman, Chief Executive Officer, and Chief Investment Officer of HKAM and was a Director of the issuer, passed away unexpectedly.
MIAMI INTERNATIONAL HOLDINGS, INC. director John Beckelman exercised stock options to acquire 8,667 shares of common stock at $12.00 per share. The options were fully vested at the time of exercise. Following the transaction, he directly holds 8,667 shares of common stock and no remaining options from this grant.
MIAMI INTERNATIONAL HOLDINGS, INC. executive Shelly Brown exercised and sold shares in a planned transaction. On April 8, 2026, Brown exercised nonqualified stock options to acquire 16,434 shares of common stock at $12.00 per share and immediately sold 16,434 shares in an open-market transaction at a weighted average price of $42.08 per share. The filing notes the options were fully vested and the trades were executed under a previously established Rule 10b5-1 Plan adopted on December 22, 2025. After these transactions, Brown directly held 325,047 shares of common stock.
MIAMI INTERNATIONAL HOLDINGS, INC. executive Edward Deitzel exercised fully vested stock options and sold the resulting shares in pre-planned trades. Over April 7–8, he exercised options to acquire a total of 12,335 shares of common stock at $12.00 per share, then sold the same 12,335 shares in open-market transactions at prices around $42.00–$42.13. These transactions were executed under a previously established Rule 10b5-1 trading plan adopted on December 30, 2025, and Deitzel continues to hold 116,221 shares of common stock directly after the activity.
MIAMI INTERNATIONAL HOLDINGS, INC. executive Shelly Brown amended her insider trading report to correct an option exercise and related holdings. On April 7, she exercised 900 Nonqualified Stock Options at $12.00 per share, acquiring 900 shares of common stock, and simultaneously sold 900 shares at $42.00 per share.
She also sold 2,357 common shares on April 6 at $41.33 per share. After these transactions, she directly held 325,047 common shares and 64,434 option-based derivative securities. A footnote states the filing reflects a correction to the original option exercise and to the amount of securities beneficially owned.
Miami International Holdings, Inc. reported the passing of Murray Stahl, a member of its Board of Directors. The company described him as a valued board member and expressed gratitude for his dedication and service.
This change in board composition was disclosed under Item 5.02 of a current report.
MIAMI INTERNATIONAL HOLDINGS, INC. executive Shelly Brown, EVP and Chief Strategy Officer, sold a total of 3,257 shares of common stock in two open-market transactions. On April 7, 2026, she sold 900 shares at about $42.00 per share. On April 6, 2026, she sold 2,357 shares at about $41.33 per share. After these sales, she directly holds 324,147 shares. The filing notes that at least one transaction was carried out under a pre-established Rule 10b5-1 trading plan, indicating the sales were pre-planned rather than timed discretionarily.