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[Form 4] MIAMI INTERNATIONAL HOLDINGS, INC. Insider Trading Activity

Filing Impact
(High)
Filing Sentiment
(Positive)
Form Type
4
Rhea-AI Filing Summary

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.

Murray Stahl e Horizon Kinetics Asset Management LLC hanno riportato operazioni societarie interne su Miami International Holdings, Inc. (MIAX). Il 28/08/2025 un modulo Form 4 mostra l'acquisto di 34.470 azioni ordinarie MIAX a 36,10 USD per azione. Dopo l'operazione indicata, la dichiarazione evidenzia una proprietà beneficiaria indiretta di 4.557.919 azioni detenute da Horizon Kinetics. La dichiarazione elenca anche diverse opzioni azionarie maturate detenute direttamente dal signor Stahl (in totale 43.131 opzioni con diversi prezzi di esercizio e scadenze) e diverse warrant maturati detenuti indirettamente da Horizon Kinetics (in totale 137.656 warrant con vari strike e date di scadenza). La dichiarazione chiarisce i ruoli del signor Stahl presso Horizon Kinetics e precisa che non esiste una proprietà beneficiaria diretta salvo eventuali interessi meramente economici.

Murray Stahl y Horizon Kinetics Asset Management LLC reportaron operaciones internas en Miami International Holdings, Inc. (MIAX). El 28/08/2025 se muestra en un Formulario 4 la compra de 34.470 acciones comunes de MIAX a $36.10 por acción. Tras la operación reportada, la declaración indica una propiedad beneficiaria indirecta de 4.557.919 acciones en posesión indirecta de Horizon Kinetics. El documento también enumera varias opciones de acciones adquiridas y ejercidas directamente por el Sr. Stahl (un total de 43.131 opciones con diferentes precios de ejercicio y fechas de vencimiento) y varias warrants adquiridos indirectamente por Horizon Kinetics (un total de 137.656 warrants con distintos precios de ejercicio y fechas de vencimiento). El documento aclara los roles del Sr. Stahl en Horizon Kinetics y señala que no existe propiedad beneficiaria directa salvo cualquier interés pecuniario.

Murray Stahl과 Horizon Kinetics Asset Management LLC은 Miami International Holdings, Inc. (MIAX)에서 내부자 거래를 보고했습니다. 2025년 8월 28일에 Form 4에 MIAX 보통주를 주당 36.10달러에 34,470주를 매수한 것으로 나와 있습니다. 보고된 거래 후, 서류는 Horizon Kinetics가 간접적으로 보유한 4,557,919주의 유익한 소유권을 명시합니다. 서류는 또한 Stahl 씨가 직접 보유한 다수의 주식 옵션(총 43,131주, 다양한 행사 가격과 만료일)과 Horizon Kinetics가 간접적으로 보유한 다수의 워런트(총 137,656주, 서로 다른 행사가와 만료일)도 기재합니다. 서류는 Stahl 씨의 Horizon Kinetics 내 역할을 명확히 하고 재산적 이해관계가 없는 한 직접적인 유익 소유권은 없다고 명시합니다.

Murray Stahl et Horizon Kinetics Asset Management LLC ont signalé des transactions d’initié chez Miami International Holdings, Inc. (MIAX). Le 28/08/2025, un formulaire Form 4 montre l’achat de 34 470 actions MIAX ordinaires à 36,10 USD l’action. Après la transaction indiquée, le dépôt indique une propriété bénéficiaire indirecte de 4 557 919 actions détenues par Horizon Kinetics. Le dépôt répertorie également plusieurs options d’achat d’actions acquises et exercées directement par M. Stahl (au total 43 131 options avec différents prix d’exercice et dates d’expiration) et plusieurs warrants détenus indirectement par Horizon Kinetics (au total 137 656 warrants avec divers prix d’exercice et dates d’expiration). Le dépôt précise les rôles de M. Stahl chez Horizon Kinetics et indique qu’il n’existe pas de propriété bénéficiaire directe sauf pour tout intérêt pécuniaire.

Murray Stahl und Horizon Kinetics Asset Management LLC meldeten Insider-Transaktionen bei Miami International Holdings, Inc. (MIAX). Am 28.08.2025 zeigt ein Form 4 den Kauf von 34.470 MIAX-Stammaktien zum Preis von 36,10 USD pro Aktie. Nach der berichteten Transaktion ergibt sich eine indirekte wirtschaftliche Eigentümerschaft an 4.557.919 Aktien, die von Horizon Kinetics gehalten werden. Die Einreichung führt außerdem mehrere direkt von Herrn Stahl gehaltene Aktienoptionen (insgesamt 43.131 Optionen mit unterschiedlichen Ausübungspreisen und Verfallsdaten) sowie mehrere indirekt von Horizon Kinetics gehaltene Warrants (137.656 Warrants mit verschiedenen Knock-Out-Preisen und Verfallsdaten) auf. Die Einreichung klärt die Rollen von Herrn Stahl bei Horizon Kinetics und weist darauf hin, dass keine direkte wirtschaftliche Eigentümerschaft besteht außer bei etwaigen finanziellen Interessen.

أبلغ موراي ستاهل وهورايزون كينيتكس لإدارة الأصول LLC عن معاملات داخلية في Miami International Holdings, Inc. (MIAX). في تاريخ 28/08/2025 يُظهر نموذج 4 شراء 34,470 سهماً من أسهم MIAX العادية بسعر 36.10 دولاراً للسهم. بعد الصفقة المعلنة، تُظهر الإفادة وجود ملكيات مستفيدة غير مباشرة تبلغ 4,557,919 سهماً تحت سيطرة Horizon Kinetics. كما تتضمن الإفادة عدداً من خيارات الأسهم الممنوحة والمفعلة مباشرةً من السيد ستاهل (مجمَّعاً 43,131 خياراً عبر أسعار تنفيذ وتواريخ انتهاء مختلفة) وعمليات warrants ممنوحة بشكل غير مباشر من Horizon Kinetics (مجمَّعة 137,656 warrant عبر أسعار تنفيذ وتواريخ انتهاء مختلفة). وتوضح الإفادة أدوار السيد ستاهل في Horizon Kinetics وتؤكد عدم وجود ملكية مستفيدة مباشرة باستثناء أي مصلحة مالية محتملة.

Murray Stahl 与 Horizon Kinetics Asset Management LLC 在 Miami International Holdings, Inc. (MIAX) 报告了内幕交易。 2025 年 8 月 28 日的 Form 4 显示以每股 36.10 美元购买了 34,470 股 MIAX 普通股。交易后，申报文件显示 Horizon Kinetics 间接持有的 4,557,919 股受益所有权。申报还列出 Stahl 先生直接持有的若干股票期权（共 43,131 份，涵盖不同的行权价和到期日）以及 Horizon Kinetics 间接持有的多项已归属的认股权证（共 137,656 份，跨越不同的行权价和到期日）。申报澄清 Stahl 先生在 Horizon Kinetics 的角色，并表示除任何经济利益外不存在直接的受益所有权。

Positive
  • Insider purchase of 34,470 shares at $36.10 on 08/28/2025 indicating additional economic exposure
  • Substantial reported indirect ownership of 4,557,919 shares by Horizon Kinetics, showing significant stakeholder interest
  • Multiple vested options and warrants are disclosed, clarifying potential future exercise activity and ownership changes
  • Filing corrects prior omissions (shares inadvertently excluded from Form 3) and discloses conversions to common stock
Negative
  • None.

Insights

TL;DR: Director and affiliated 10% owner reported a purchase and sizable indirect holdings, plus vested options and warrants.

The Form 4 documents a 34,470-share open-market purchase at $36.10 by or on behalf of accounts affiliated with Horizon Kinetics on 08/28/2025, increasing reported indirect beneficial ownership to 4,557,919 shares. The filing distinguishes between directly held, fully vested options in Mr. Stahls name and indirectly held warrants held by Horizon Kinetics. For investors, the combination of an outright purchase and substantial indirect stake signals continued economic exposure from the asset manager; the presence of multiple vested derivative instruments creates potential future share issuance if exercised. This disclosure is routine but material to ownership structure and dilution considerations.

TL;DR: Chairman/CEO of HKAM is reported as affiliated with a large indirect position and holds vested options; filing clarifies disclosure and disclaimers.

The filing provides clear role disclosure: Murray Stahl is Chairman, CEO, and CIO of Horizon Kinetics Asset Management LLC and the Form notes he does not exercise investment discretion for the managed accounts reported. The Form corrects prior omissions by including shares inadvertently excluded from an earlier Form 3 and identifies converted preferred and non-voting shares now reflected as common stock. The signature by an attorney-in-fact and the explanatory footnotes follow standard Section 16 protocols. This is a governance-appropriate, corrective and clarifying filing rather than an operational disclosure.

Murray Stahl e Horizon Kinetics Asset Management LLC hanno riportato operazioni societarie interne su Miami International Holdings, Inc. (MIAX). Il 28/08/2025 un modulo Form 4 mostra l'acquisto di 34.470 azioni ordinarie MIAX a 36,10 USD per azione. Dopo l'operazione indicata, la dichiarazione evidenzia una proprietà beneficiaria indiretta di 4.557.919 azioni detenute da Horizon Kinetics. La dichiarazione elenca anche diverse opzioni azionarie maturate detenute direttamente dal signor Stahl (in totale 43.131 opzioni con diversi prezzi di esercizio e scadenze) e diverse warrant maturati detenuti indirettamente da Horizon Kinetics (in totale 137.656 warrant con vari strike e date di scadenza). La dichiarazione chiarisce i ruoli del signor Stahl presso Horizon Kinetics e precisa che non esiste una proprietà beneficiaria diretta salvo eventuali interessi meramente economici.

Murray Stahl y Horizon Kinetics Asset Management LLC reportaron operaciones internas en Miami International Holdings, Inc. (MIAX). El 28/08/2025 se muestra en un Formulario 4 la compra de 34.470 acciones comunes de MIAX a $36.10 por acción. Tras la operación reportada, la declaración indica una propiedad beneficiaria indirecta de 4.557.919 acciones en posesión indirecta de Horizon Kinetics. El documento también enumera varias opciones de acciones adquiridas y ejercidas directamente por el Sr. Stahl (un total de 43.131 opciones con diferentes precios de ejercicio y fechas de vencimiento) y varias warrants adquiridos indirectamente por Horizon Kinetics (un total de 137.656 warrants con distintos precios de ejercicio y fechas de vencimiento). El documento aclara los roles del Sr. Stahl en Horizon Kinetics y señala que no existe propiedad beneficiaria directa salvo cualquier interés pecuniario.

Murray Stahl과 Horizon Kinetics Asset Management LLC은 Miami International Holdings, Inc. (MIAX)에서 내부자 거래를 보고했습니다. 2025년 8월 28일에 Form 4에 MIAX 보통주를 주당 36.10달러에 34,470주를 매수한 것으로 나와 있습니다. 보고된 거래 후, 서류는 Horizon Kinetics가 간접적으로 보유한 4,557,919주의 유익한 소유권을 명시합니다. 서류는 또한 Stahl 씨가 직접 보유한 다수의 주식 옵션(총 43,131주, 다양한 행사 가격과 만료일)과 Horizon Kinetics가 간접적으로 보유한 다수의 워런트(총 137,656주, 서로 다른 행사가와 만료일)도 기재합니다. 서류는 Stahl 씨의 Horizon Kinetics 내 역할을 명확히 하고 재산적 이해관계가 없는 한 직접적인 유익 소유권은 없다고 명시합니다.

Murray Stahl et Horizon Kinetics Asset Management LLC ont signalé des transactions d’initié chez Miami International Holdings, Inc. (MIAX). Le 28/08/2025, un formulaire Form 4 montre l’achat de 34 470 actions MIAX ordinaires à 36,10 USD l’action. Après la transaction indiquée, le dépôt indique une propriété bénéficiaire indirecte de 4 557 919 actions détenues par Horizon Kinetics. Le dépôt répertorie également plusieurs options d’achat d’actions acquises et exercées directement par M. Stahl (au total 43 131 options avec différents prix d’exercice et dates d’expiration) et plusieurs warrants détenus indirectement par Horizon Kinetics (au total 137 656 warrants avec divers prix d’exercice et dates d’expiration). Le dépôt précise les rôles de M. Stahl chez Horizon Kinetics et indique qu’il n’existe pas de propriété bénéficiaire directe sauf pour tout intérêt pécuniaire.

Murray Stahl und Horizon Kinetics Asset Management LLC meldeten Insider-Transaktionen bei Miami International Holdings, Inc. (MIAX). Am 28.08.2025 zeigt ein Form 4 den Kauf von 34.470 MIAX-Stammaktien zum Preis von 36,10 USD pro Aktie. Nach der berichteten Transaktion ergibt sich eine indirekte wirtschaftliche Eigentümerschaft an 4.557.919 Aktien, die von Horizon Kinetics gehalten werden. Die Einreichung führt außerdem mehrere direkt von Herrn Stahl gehaltene Aktienoptionen (insgesamt 43.131 Optionen mit unterschiedlichen Ausübungspreisen und Verfallsdaten) sowie mehrere indirekt von Horizon Kinetics gehaltene Warrants (137.656 Warrants mit verschiedenen Knock-Out-Preisen und Verfallsdaten) auf. Die Einreichung klärt die Rollen von Herrn Stahl bei Horizon Kinetics und weist darauf hin, dass keine direkte wirtschaftliche Eigentümerschaft besteht außer bei etwaigen finanziellen Interessen.

SEC Form 4
FORM 4 UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934
or Section 30(h) of the Investment Company Act of 1940
OMB APPROVAL
OMB Number: 3235-0287
Estimated average burden
hours per response: 0.5
Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).
1. Name and Address of Reporting Person*
STAHL MURRAY
(Last) (First) (Middle)
470 PARK AVE S
8TH FLOOR SOUTH
(Street)
NEW YORK NY 10016
(City) (State) (Zip)
2. Issuer Name and Ticker or Trading Symbol
MIAMI INTERNATIONAL HOLDINGS, INC. [ MIAX ] 		5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)
X Director 10% Owner
Officer (give title below) Other (specify below)
3. Date of Earliest Transaction (Month/Day/Year)
08/28/2025
4. If Amendment, Date of Original Filed (Month/Day/Year)
 6. Individual or Joint/Group Filing (Check Applicable Line)
Form filed by One Reporting Person
X Form filed by More than One Reporting Person
Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3) 2. Transaction Date (Month/Day/Year) 2A. Deemed Execution Date, if any (Month/Day/Year) 3. Transaction Code (Instr. 8) 4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5) 5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4) 6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 7. Nature of Indirect Beneficial Ownership (Instr. 4)
Code V Amount (A) or (D) Price
Common Stock 08/28/2025 P 34,470 A $36.1 4,557,919(1)(2)(3) I Horizon Kinetics Asset Management LLC
Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned
(e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3) 2. Conversion or Exercise Price of Derivative Security 3. Transaction Date (Month/Day/Year) 3A. Deemed Execution Date, if any (Month/Day/Year) 4. Transaction Code (Instr. 8) 5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5) 6. Date Exercisable and Expiration Date (Month/Day/Year) 7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4) 8. Price of Derivative Security (Instr. 5) 9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4) 10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4) 11. Nature of Indirect Beneficial Ownership (Instr. 4)
Code V (A) (D) Date Exercisable Expiration Date Title Amount or Number of Shares
OPTIONS $16.14(4) 08/13/2025 05/31/2031 Miami International Holdings Inc 2,500 2,500 D
OPTIONS $16.14(4) 08/13/2025 07/31/2031 Miami International Holdings Inc 7,500 7,500 D
OPTIONS $25.98(4) 08/13/2025 06/30/2032 Miami International Holdings Inc 10,000 10,000 D
OPTIONS $19.84(4) 08/13/2025 03/26/2033 Miami International Holdings Inc 14,331 14,331 D
Warrants $20.5(1)(5) 08/13/2025 11/15/2026 Miami International Holdings Inc 24,878 24,878 I Horizon Kinetics Asset Management LLC
Warrants $20.5(1)(5) 08/13/2025 02/05/2027 Miami International Holdings Inc 27,561 27,561 I Horizon Kinetics Asset Management LLC
Warrants $15(1)(5) 08/13/2025 04/08/2026 Miami International Holdings Inc 21,290 21,290 I Horizon Kinetics Asset Management LLC
Warrants $20.5(1)(5) 08/13/2025 10/17/2026 Miami International Holdings Inc 38,927 38,927 I Horizon Kinetics Asset Management LLC
1. Name and Address of Reporting Person*
STAHL MURRAY
(Last) (First) (Middle)
470 PARK AVE S
8TH FLOOR SOUTH
(Street)
NEW YORK NY 10016
(City) (State) (Zip)
Relationship of Reporting Person(s) to Issuer
X Director 10% Owner
Officer (give title below) Other (specify below)
1. Name and Address of Reporting Person*
HORIZON KINETICS ASSET MANAGEMENT LLC
(Last) (First) (Middle)
470 PARK AVE S
8TH FLOOR SOUTH
(Street)
NEW YORK NY 10016
(City) (State) (Zip)
Relationship of Reporting Person(s) to Issuer
Director X 10% Owner
Officer (give title below) Other (specify below)
Explanation of Responses:
1. Murray Stahl serves as Chairman, Chief Executive Officer, and Chief Investment Officer of Horizon Kinetics Asset Management LLC ("HKAM"), which manages funds and accounts (the "Managed Accounts") that hold securities of the Issuer. Mr. Stahl does not exercise investment discretion with respect to the securities of the Issuer that are beneficially owned by the Managed Accounts. Mr. 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 the Mr. Stahl is the beneficial owner of such securities for purposes of Section 16 or any other purpose.
2. Includes 5,000 shares of Series B Preferred Stock that have been converted into Common Stock on a one-for-one basis upon the closing of the Company's initial public offering and which have no expiration date and 14,998 shares of Non-Voting Common Stock that have been converted into shares of Common Stock on a one-for-one basis upon the closing of the Company's IPO and which have no expiration date.
3. Includes Shares that were inadvertently excluded from the Form 3 filing made on August 13, 2025
4. The Options given to Mr. Stahl are fully vested.
5. The Warrants are currently vested and presently exercisable until the expiration date show.
/s/ Jay Kesslen, attorney-in-fact 09/30/2025
** Signature of Reporting Person Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.

Source: View Original Filing on SEC EDGAR

FAQ

What insider transaction was reported for MIAX on 08/28/2025?

The Form 4 reports a purchase of 34,470 shares of MIAMI INTERNATIONAL HOLDINGS, INC. common stock at $36.10 per share on 08/28/2025.

How many MIAX shares does Horizon Kinetics report beneficially owning?

The filing shows Horizon Kinetics Asset Management LLC indirectly beneficially owns 4,557,919 shares following the reported transaction.

Does Murray Stahl hold options or warrants in MIAX?

Yes. The Form 4 lists fully vested options held directly by Murray Stahl totaling 43,131 options across multiple exercise prices and expirations, and multiple warrants held indirectly by Horizon Kinetics totaling 137,656 warrants.

Did the Form 4 correct any prior filing errors?

Yes. The filing states it includes shares that were inadvertently excluded from a Form 3 filed on 08/13/2025 and notes converted Series B Preferred and Non-Voting Common shares that became common stock upon the IPO.

What relationship does Murray Stahl have to Horizon Kinetics and MIAX?

The filing identifies Murray Stahl as Chairman, Chief Executive Officer, and Chief Investment Officer of Horizon Kinetics; Horizon Kinetics is reported as a 10% owner of MIAX.
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Miami International Holdings, Inc.

NYSE:MIAX

MIAX Rankings

#1668 Ranked by Market Cap
N/A Ranked by Dividends

MIAX Latest News

Oct 7, 2025
Miami International Holdings Reports Trading Results for September 2025
Sep 23, 2025
Miami International Holdings Announces Timeline to Support Trading of Financial Futures on MIAX Futures
Sep 16, 2025
Miami International Holdings Launches Next-Generation Options Trading Floor in Miami
Sep 8, 2025
Miami International Holdings Reports Trading Results for August 2025
Aug 13, 2025
Miami International Holdings Announces Pricing of Initial Public Offering

MIAX Latest SEC Filings

Oct 6, 2025
[Form 4] MIAMI INTERNATIONAL HOLDINGS, INC. Insider Trading Activity
Sep 30, 2025
[Form 4] MIAMI INTERNATIONAL HOLDINGS, INC. Insider Trading Activity
Sep 15, 2025
[Form 4] MIAMI INTERNATIONAL HOLDINGS, INC. Insider Trading Activity
Sep 15, 2025
[Form 4] MIAMI INTERNATIONAL HOLDINGS, INC. Insider Trading Activity
Sep 11, 2025
[Form 4] Miami International Holdings, Inc. Insider Trading Activity

MIAX Stock Data

3.44B
15.00M
11.27%
19.01%
1.88%
Capital Markets
Financial Services
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United States
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