Welcome to our dedicated page for Miami Intl Hldg 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.
The SEC filings of Miami International Holdings, Inc. (NYSE: MIAX) provide detailed information about its capital markets activity, segment reporting and regulatory disclosures as an exchange operator. Through documents such as Form S-1 and Form 8-K, the company describes its business structure, operating segments and equity transactions.
In its Form S-1 registration statement, Miami International Holdings identifies operating segments associated with options, equities, futures and international markets, along with a corporate/non-segment category. The filing references revenue categories including transaction and clearing fees, access fees, market data fees and other products and services, giving investors insight into how the company characterizes its exchange-related activities.
Recent Form 8-K filings highlight specific events. An 8-K dated December 15, 2025 discloses unregistered sales of equity securities, including common stock issued upon conversion of a convertible promissory note and upon warrant exercises, and notes that aggregate unregistered issuances exceeded a threshold relative to shares outstanding as of a prior date. The same filing also describes the completion of a public secondary offering in which existing stockholders sold shares of common stock, with the company stating that it did not sell shares or receive proceeds.
Other 8-K reports address topics such as quarterly financial results, changes in the board of directors and the announcement of an agreement to sell a majority stake in MIAX Derivatives Exchange (MIAXdx) to Robinhood Markets, Inc. in partnership with Susquehanna International Group. These filings illustrate how the company uses current reports to communicate material events, corporate governance changes and strategic transactions.
On Stock Titan’s MIAX filings page, users can review these SEC documents as they are made available through EDGAR. AI-powered tools can help summarize lengthy forms such as S-1 and 8-K, highlight key segment and revenue disclosures, and surface notable equity issuance and offering details, making it easier to understand the regulatory information Miami International Holdings provides.
Insider purchase and holdings disclosed. Murray Stahl and Horizon Kinetics Asset Management LLC reported acquisitions and existing derivative holdings in Miami International Holdings, Inc. (MIAX). On 09/26/2025 a purchase (code P) of Common Stock at $41.76 was reported, leaving 4,557,923 shares beneficially owned indirectly by Horizon Kinetics. The filing also lists vested, exercisable stock options awarded 08/13/2025 (totaling 34,831 options across four strike prices: $16.14, $25.98, $19.84) held directly, and multiple warrants held indirectly by Horizon Kinetics (totaling 137,636 warrants across various strikes and expiration dates). Murray Stahl is identified as Chairman, CEO, and CIO of HKAM and disclaims direct investment discretion over the managed accounts' holdings.
Murray Stahl and Horizon Kinetics Asset Management LLC reported insider transactions in Miami International Holdings, Inc. (MIAX). On 08/28/2025 a Form 4 shows a purchase of 34,470 shares of MIAX common stock at $36.10 per share. After the reported transaction, the filing shows beneficial ownership of 4,557,919 shares held indirectly by Horizon Kinetics. The filing also lists several vested stock options held directly by Mr. Stahl (totaling 43,131 options across multiple grant exercise prices and expirations) and multiple vested warrants held indirectly by Horizon Kinetics (totaling 137,656 warrants across different strikes and expiration dates). The filing clarifies Mr. Stahls roles at Horizon Kinetics and disclaims direct beneficial ownership except for any pecuniary interest.
John Smollen, EVP Traded Products & Relation of Miami International Holdings, Inc. (MIAX), reported option exercises on 09/11/2025 and subsequent net settlement for tax withholding. The filing shows two nonqualified stock option exercises of 125,001 and 24,999 shares at an exercise price of $12 per share, and the surrender of 52,054 shares to satisfy tax-withholding obligations at an indicated price of $37.39 per share. The options were fully vested and exercisable on 09/17/2025. Following the transactions the reporting person beneficially owned 166,119 shares directly. The form is signed by an attorney-in-fact on 09/15/2025.
Miami International Holdings insider Edward Deitzel completed option exercises and share purchases in September 2025, increasing his direct holdings. On 09/09/2025 he exercised 62,500 nonqualified options with a $12 exercise price and acquired 62,500 common shares via that exercise. The same day 38,090 shares were surrendered to the company to satisfy tax withholding related to the net settlement of those exercises; this surrender is not a sale. On 09/10/2025 he exercised 16,666 incentive stock options at $12, and on 09/11/2025 he purchased 16,666 shares at $12. Following these transactions his reported beneficial ownership totaled 122,963 shares. All options exercised were fully vested.
Jayabalan Harish, EVP, CISO and CRO of Miami International Holdings, Inc. (MIAX), reported option exercises and resulting share ownership changes on 09/09/2025. He exercised 21,999 incentive stock options and 3,001 nonqualified stock options at a $12 exercise price, resulting in 25,000 shares acquired that day. The filing shows 72,384 shares beneficially owned after the first reported acquisition line and 75,385 after the second; a separate line records a net disposition of 1,980 shares at $37.30 representing shares surrendered to satisfy tax withholding on the net settlement of exercised options (not a sale). The reporting was signed by an attorney-in-fact on 09/11/2025.
Shelly Brown, EVP of Strategic Planning & Business Development at Miami International Holdings, Inc. (MIAX), reported a disposition of 16,283 shares of MIAX common stock on 09/10/2025 at a reported price of $36.81 per share. After the transaction, she beneficially owns 311,699 shares, held directly.
The filing explains these shares were surrendered to the company to satisfy tax withholding in connection with the net settlement of restricted stock awards and explicitly states this was not a sale by the reporting person. The Form 4 was submitted by an attorney-in-fact on behalf of the reporting person.
Miami International Holdings insider Shelly Brown reported a change in beneficial ownership on Form 4. The filing shows that on 08/26/2025 Ms. Brown had 11,047 shares of common stock surrendered to the company to satisfy tax withholding obligations related to the net settlement of restricted stock awards; the filing notes this was not a sale. Following the transaction her beneficial ownership is reported as 327,982 shares. The Form 4 was signed by an attorney-in-fact on 08/28/2025 and discloses Ms. Brown's role as EVP, Strategic Planning & BD.
Thomas P. Gallagher, Chairman & CEO and a director of Miami International Holdings, Inc. (MIAX), reported changes in his beneficial ownership on Form 4. On 08/26/2025 he disposed of 192,220 common shares under Code F at a price of $33.90 per share; the filing states these shares were surrendered to satisfy tax withholding related to net settlement of restricted stock awards and do not represent a sale. Following the reported transactions, Mr. Gallagher is shown as beneficially owning 1,848,274 shares indirectly through Gallagher Investments, LLC. The filing also corrects prior holdings to reflect an additional 2,000 shares purchased on 08/13/2025 and held jointly with his spouse. The form was signed by an attorney-in-fact on 08/28/2025.
Amendment No. 1 to Schedule 13D discloses updated ownership by Thomas P. Gallagher and Gallagher Investments LLC in Miami International Holdings, Inc. (MIAX) following the company's initial public offering. The Reporting Persons report beneficial ownership of 4,036,237 shares of common stock, representing 4.9% of the 80,799,866 shares outstanding as of August 26, 2025. Holdings include individually held shares, shares held by Gallagher Investments, and stock options exercisable within 60 days. Gallagher Investments surrendered 192,220 shares and $12.5 million in cash to satisfy tax withholding related to IPO-related vesting. The filing is described as a final amendment and an "exit filing" reflecting that the Reporting Persons ceased to beneficially own more than 5% as of August 26, 2025.
Thomas P. Gallagher and Gallagher Investments LLC reported beneficial ownership of 4,226,457 shares (5.1% of outstanding common stock) of Miami International Holdings, Inc. The filing shows Gallagher holds 573,963 shares directly, 12,000 jointly with his spouse, and options exercisable for 63,138 shares; Gallagher Investments holds 2,040,494 shares and options exercisable for 1,536,862 shares. Many shares resulted from conversions tied to the issuer's initial public offering and a small purchase of 12,000 IPO shares on August 14, 2025. Holdings are declared for investment with a 180-day lock-up and Gallagher serves as the issuer's Chairman and CEO, retaining voting and dispositive control over the shares reported.