As of November 6, 2026, 3 holders' latest Schedule 13D or 13G filings report owning 5% or more of Miami International Holdings Inc. The largest reported stake is Horizon Kinetics Asset Management LLC's, at 7.8%. 10 filings are on record since August 21, 2025 (Schedule 13D/A, May 21, 2026).
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Key facts
- · Reporting person: BlackRock, Inc. · Sole voting: 5,977,233 · Shared voting: 0 · Sole dispositive: 6,124,616 · Shared dispositive: 0 · SCHEDULE 13G/A, 2026-10-27
- · Reporting person: T. Rowe Price Investment Management, Inc. · Sole voting: 5,019,927 · Shared voting: 0 · Sole dispositive: 5,032,970 · Shared dispositive: 0 · SCHEDULE 13G, 2026-08-14
- · Holder: BlackRock, Inc. · Percent: 5.1% · SCHEDULE 13G
- · Holder: Horizon Kinetics Asset Management LLC · Percent: 7.8% · SCHEDULE 13D/A
- · Holder: Horizon Kinetics Asset Management LLC · Percent: 12.2% · SCHEDULE 13D/A
Miami International Holdings Inc has 10 Schedule 13D or 13G filings on record since 2025-08-21. 3 holders' latest filing reports 5% or more of common stock. Each figure below is the holder's own, as filed, with the filing linked.
Holders
| Holder | Percent | Shares | Latest | Event date |
|---|---|---|---|---|
| Horizon Kinetics Asset Management LLC | 7.8% | 7,400,316 | SCHEDULE 13D/A, 2026-05-21 | 2026-05-19 |
| BlackRock, Inc. | 6.2% | 6,124,616 | SCHEDULE 13G/A, 2026-10-27 | 2026-09-30 |
| T. Rowe Price Investment Management, Inc. | 5.3% | 5,032,970 | SCHEDULE 13G, 2026-08-14 | 2026-06-30 |
| 4.9% | 4,036,237 | SCHEDULE 13D/A, 2025-08-28 | 2025-08-26 |
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More on Miami International Holdings Inc and the records around it.
Miami International Holdings Inc elsewhere on the record
- IPO filing Dec 2025
- Who owns it
Companies that share a holder
- HORIZON KINETICS ASSET MANAGEMENT LLC also filed stake reports on 13 other companies: LandBridge Co LLC (Nov 2026), EagleRock Land, LLC (Jul 2026), WhiteHawk Minerals Corp. (Jul 2026)
- T. Rowe Price Investment Management, Inc. also filed stake reports on 167 other companies: CABALETTA BIO INC (Nov 2026), MADISON SQUARE GARDEN SPORTS CORP (Nov 2026), MSG RANGERS CORP (Nov 2026)
- BlackRock, Inc. also filed stake reports on 1596 other companies: AvePoint, Inc. (Nov 2026), BIOMARIN PHARMACEUTICAL INC (Nov 2026), MSG RANGERS CORP (Nov 2026)
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Voting and dispositive power, as filed
| Reporting person | Sole voting | Shared voting | Sole dispositive | Shared dispositive | Filing |
|---|---|---|---|---|---|
| BlackRock, Inc. | 5,977,233 | 0 | 6,124,616 | 0 | SCHEDULE 13G/A, 2026-10-27 |
| T. Rowe Price Investment Management, Inc. | 5,019,927 | 0 | 5,032,970 | 0 | SCHEDULE 13G, 2026-08-14 |
The latest filing identifies Miami International Holdings Inc by CUSIP 59356Q108 and gives its principal executive office as 7 Roszel Road, Suite 1A, Princeton, NJ 08540 (SCHEDULE 13G/A, 2026-10-27).
Purpose of Transaction (Item 4)
Horizon Kinetics Asset Management LLC
HKAM acquired the securities reported herein on behalf of the Managed Accounts for investment purposes. In the ordinary course of its business, HKAM intends to regularly review its equity interest in the Issuer and may, from time to time, acquire additional shares or other securities of the Issuer. While HKAM has no present intention to dispose of all or any portion of the shares beneficially owned by Managed Accounts, it may sell shares from time to time for a number of reasons, not limited to client requests, regulatory or investment limitations or other reasons. Any such sales of securities of the Issuer may be in the open market, privately negotiated transactions or otherwise. On May 19, 2026, HKAM distributed 4,084,261 shares in-kind on a pro rata basis without consideration to the beneficial owners of the Managed Accounts in response to client requests.Item 4 of the SCHEDULE 13D/A filed 2026-05-21
Thomas P. Gallagher
The Reporting Persons acquired all of their securities for investment purposes only and are being held as a long-term investment. The Reporting Persons intend to continuously review their investment in the Issuer and may in the future determine to acquire additional securities of the Issuer or dispose of the securities of the Issuer owned by them or take any other available course of action, including surrendering or selling shares back to the Issuer for tax withholding obligations. Notwithstanding anything contained herein, the Reporting Persons specifically reserve the right to change their intention with respect to any or all of such matters. Mr. Gallagher is the Chairman and Chief Executive Officer of the Issuer and acquired his securities in that capacity. As a result, Mr. Gallagher may have influence over the corporate activities of the Issuer, including activities that may relate to items described in subparagraphs (a) through (j) of Item 4 of Schedule 13D. The Reporting Persons do not have any present plans or proposals as of the date hereof that relate to or would result in any of the transactions described in subparagraphs (a) through (j) of Item 4 of Schedule 13D.Item 4 of the SCHEDULE 13D/A filed 2025-08-28
Timeline
| Filed | Holder | Percent | Filing |
|---|---|---|---|
| 2025-08-21 | Horizon Kinetics Asset Management LLC | 10.7% | SCHEDULE 13D |
| 2025-08-21 | Thomas P. Gallagher | 5.1% | SCHEDULE 13D |
| 2025-08-28 | Thomas P. Gallagher | 4.9% | SCHEDULE 13D/A |
| 2025-11-26 | Horizon Kinetics Asset Management LLC | 11.7% | SCHEDULE 13D/A |
| 2026-04-14 | Horizon Kinetics Asset Management LLC | 12.1% | SCHEDULE 13D/A |
| 2026-04-28 | Horizon Kinetics Asset Management LLC | 12.2% | SCHEDULE 13D/A |
| 2026-05-21 | Horizon Kinetics Asset Management LLC | 7.8% | SCHEDULE 13D/A |
| 2026-07-29 | BlackRock, Inc. | 5.1% | SCHEDULE 13G |
| 2026-08-14 | T. Rowe Price Investment Management, Inc. | 5.3% | SCHEDULE 13G |
| 2026-10-27 | BlackRock, Inc. | 6.2% | SCHEDULE 13G/A |
Questions about who owns Miami International Holdings Inc
Who owns Miami International Holdings Inc?
On this page, 3 holders' latest ownership filings report 5% or more of Miami International Holdings Inc: Horizon Kinetics Asset Management LLC (7.8%, Schedule 13D/A, filed 2026-05-21), BlackRock, Inc. (6.2%, Schedule 13G/A, filed 2026-10-27) and T. Rowe Price Investment Management, Inc. (5.3%, Schedule 13G, filed 2026-08-14).
Who are the largest shareholders of Miami International Holdings Inc?
By the share each holder's latest filing reports, the largest holders of Miami International Holdings Inc on this page are Horizon Kinetics Asset Management LLC (7.8%), BlackRock, Inc. (6.2%) and T. Rowe Price Investment Management, Inc. (5.3%).
When did Horizon Kinetics Asset Management LLC buy into Miami International Holdings Inc?
The filings give report dates, not purchase dates. The earliest filing from Horizon Kinetics Asset Management LLC on this page is the Schedule 13D, filed 2025-08-21, reporting 10.7%; its latest, Schedule 13D/A filed 2026-05-21, reports 7.8%.
Is this an audit or a full list?
Neither. The ownership list on this page covers only Schedule 13D and 13G filings, which holders make once they own 5% or more of a class of shares (an amendment can report a stake that has since fallen below 5%); 10 such filings are shown here. It is not an audit and not a full cap table: holders who never reached 5% are not listed, and a stake can change after its latest filing.
Also on the record for Miami International Holdings Inc
| Date | Record | Figure | Our page | Source |
|---|---|---|---|---|
| April 27, 2026 | Leadership change filing (Form 8-K, Item 5.02) | — | Leadership changes | Source |
| December 15, 2025 | IPO filing, Form 424B4 | $23 a share | IPO filings | Source |
| December 9, 2025 | IPO filing, Form S-1 | — | IPO filings | Source |
| August 14, 2025 | IPO filing, Form 424B4 | $23 a share | IPO filings | Source |
| August 4, 2025 | IPO filing, Form S-1/A | $19 to $21 a share | IPO filings | Source |
| July 18, 2025 | IPO filing, Form S-1 | — | IPO filings | Source |
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Where this comes from
Anyone who comes to own more than 5% of a class of a listed company's voting shares has to tell the SEC. A holder who may seek to change or influence the company files Schedule 13D, and has to say in Item 4, "Purpose of Transaction", what it intends to do. A holder with no such intent, such as many index and passive funds, may file the shorter Schedule 13G. Both are amended when the stake changes, including when it falls below 5%.
Every row here is one of those filings, linked to the filing itself. Percentages and share counts are exactly as the holder filed them, for the holder the filing names; an amendment showing a lower figure is shown as filed. Item 4 text is quoted word for word. Where a 13D's Item 4 contains a sentence stating a definite intent to influence the company, that sentence is marked and quoted; the page does not describe the holder or its motives beyond the words it filed. Nothing here is investment advice.