Every Form 4 that Miami International Holdings, Inc. (MIAX) has filed with the SEC in the last 12 months is listed below, newest first, and each one links through to the document itself with the summary and the scores our analysis gives it.
A Form 4 covers the transactions officers, directors and large holders report, so if you follow MIAX and want that one kind of document rather than the whole filing history, this is the page to keep. The company's other filings, of every form, are on the full MIAX filings page.
MIAMI INTERNATIONAL HOLDINGS, INC. director Murray Stahl reported an indirect open‑market purchase of 7,200 shares of common stock at $43.08 per share through accounts managed by Horizon Kinetics Asset Management LLC. Those accounts held 4,633,842 shares of the issuer’s common stock after this transaction.
Stahl also reported fully vested option positions held directly, with post‑transaction holdings of 7,500 options, 10,000 options, 14,331 options, and 2,500 options as of March 5, 2026.
Miami International Holdings, Inc. reported an amended insider transaction involving accounts managed by Horizon Kinetics Asset Management LLC. On March 4, 2026, those managed accounts bought 7,200 shares of Common Stock of MIAX at $43.38 per share, recorded as indirect ownership through Horizon Kinetics.
Murray Stahl, a director of the company and Chairman, Chief Executive Officer, and Chief Investment Officer of Horizon Kinetics Asset Management, is associated with these accounts but does not exercise investment discretion over their MIAX securities and disclaims beneficial ownership except for any pecuniary interest. The amendment also updates fully vested option holdings reported directly in his name.
MIAMI INTERNATIONAL HOLDINGS, INC. reported that ten percent owner Horizon Kinetics Asset Management LLC (HKAM) exercised warrants for a total of 112,656 shares of common stock on March 2, 2026. The warrants were exercised on a cashless basis, with the issuer withholding 53,578 shares to cover the exercise price and issuing 59,078 shares to HKAM. The filing also shows HKAM reporting an open-market sale of 53,578 common shares at $40.92 per share, leaving HKAM with 4,619,442 common shares held indirectly. Director Murray Stahl is shown with several fully vested option positions held directly, with updated post‑transaction option balances and no new option exercises disclosed.
MIAMI INTERNATIONAL HOLDINGS, INC. director Murray Stahl reported an indirect open‑market purchase of 7,200 shares of Common Stock of MIAX on March 4, 2026 at $43.38 per share. The shares are held in managed accounts of Horizon Kinetics Asset Management LLC, which now report 4,696,666 shares following the transaction.
The filing also lists fully vested options held directly by Mr. Stahl, with post‑transaction holdings of 7,500, 10,000, 14,331, and 2,500 options across several grants. The footnotes state that Mr. Stahl does not exercise investment discretion over the managed accounts and disclaims beneficial ownership except for any pecuniary interest.
MIAMI INTERNATIONAL HOLDINGS, INC. insider activity centers on Horizon Kinetics Asset Management LLC (HKAM), a ten percent owner associated with director Murray Stahl. HKAM exercised warrants to purchase 341,522 shares of common stock at the exercise prices noted.
According to the disclosure, HKAM used a cashless exercise structure, with the issuer withholding 121,054 warrant shares to pay the exercise price and issuing 129,102 shares of common stock to HKAM. After these transactions, HKAM’s indirect common stock holdings stood at 4,689,466 shares. Separately, Mr. Stahl holds fully vested options as reported.
MIAMI INTERNATIONAL HOLDINGS, INC. executive Douglas M. Schafer Jr., EVP and CIO, reported a Form 4 transaction involving 32,565 shares of common stock on February 18, 2026. The shares were surrendered back to the company to cover tax withholding on restricted stock awards, and the filing states this does not represent a market sale. After this tax-withholding disposition, he directly owns 396,681 shares.
MIAMI INTERNATIONAL HOLDINGS, INC. executive Edward Deitzel reported an administrative share transaction related to taxes. On February 18, 2026, he surrendered 6,035 shares of Common Stock at $40.89 per share to the company to satisfy tax withholding obligations tied to restricted stock awards.
A footnote explains this was a tax-withholding disposition and explicitly states it does not represent a sale by the reporting person. After this transaction, Deitzel directly owned 116,928 shares of Common Stock.
MIAMI INTERNATIONAL HOLDINGS, INC. executive Shelly Brown reported a Form 4 transaction involving the company’s common stock. On this date, 19,902 shares were surrendered to the company at $40.89 per share to satisfy tax withholding obligations tied to restricted stock awards, and Brown held 325,129 shares afterward.
MIAMI INTERNATIONAL HOLDINGS, INC. executive Douglas M. Schafer Jr., EVP and CIO, reported a tax-related share disposition. On February 10, 2026, 108,550 shares of common stock at $41.33 per share were surrendered to the company to cover tax withholding for restricted stock awards and are explicitly described as not a sale by the reporting person.
After this transaction, Schafer directly beneficially owned 429,246 common shares of the company.
Miami International Holdings, Inc. Chairman and CEO Thomas P. Gallagher, also a director, reported a Form 4 transaction involving company common stock. On February 10, 2026, 50,100 shares were disposed of at $41.33 per share in a transaction coded “F.”
According to the footnote, these shares were surrendered back to the company to satisfy tax withholding and remittance obligations related to the net settlement of restricted stock awards and do not represent an open-market sale. After this tax-withholding disposition, Gallagher directly beneficially owned 535,863 shares of common stock.
Miami International Holdings, Inc. chairman and CEO reported a transfer of shares to a family member. On 12/23/2025, he made a bona fide gift of 2,000 shares of common stock to his son. The shares given are subject to a lock-up agreement that he entered into on December 11, 2025, and the son has agreed to be bound by that agreement.
After this gift, he beneficially owns 585,963 shares of Miami International Holdings common stock. This total includes 12,000 shares held jointly with his spouse with right of survival. The transaction is reported as a gift, so no price is associated with the transfer.
Miami International Holdings, Inc. executive leadership reported multiple stock option exercises that increased direct ownership of the company’s common stock. The reporting person is an officer serving as EVP and Chief Strategy Officer.
On 12/16/2025, the officer exercised incentive stock options at an exercise price of $12 per share in three separate transactions for 16,666, 8,333, and 8,333 shares of common stock. Following these transactions, the officer beneficially owned 345,031 shares of common stock directly. The derivative securities table shows the related incentive stock option positions reduced to 0 derivative securities beneficially owned after the exercises, and the options are described as fully vested.
Miami International Holdings, Inc. reported that its EVP and CFO completed several incentive stock option exercises in company stock. On December 16, 2025, the executive exercised options to acquire 22,221 common shares at $13.50, 6,195 shares at $16.14, and 5,040 shares at $19.84.
After these transactions, the executive directly beneficially owned 127,612 shares of common stock. The filing also shows an incentive stock option with an exercise price of $19.84 for 5,040 shares expiring on March 28, 2033, and notes that 5,040 additional shares subject to this option are scheduled to vest on March 29, 2026, if the executive continues in service with the company or its subsidiaries.
Miami International Holdings, Inc. reported an insider-related purchase of 2,439 shares of common stock on 12/12/2025 at $41 per share. The transaction was reported as an indirect acquisition through Horizon Kinetics Asset Management LLC, bringing the total indirectly beneficially owned common shares to 4,560,364.
The report also lists fully vested stock options held directly by the insider for 7,500, 10,000, 14,331 and 2,500 underlying shares at exercise prices between $16.14 and $25.98, as well as several currently vested warrants held indirectly through Horizon Kinetics Asset Management LLC for 24,878, 27,561, 21,290 and 38,927 underlying shares. Murray Stahl, who leads Horizon Kinetics Asset Management LLC, disclaims beneficial ownership except for any pecuniary interest.