Who owns Miami International Holdings (MIAX)
Which tracked institutional funds hold MIAX, how they are positioned, and who is buying versus exiting — from SEC Form 13F-HR filings. See MIAX company fundamentals →
Ownership as of the 2026-Q2 13F filings (latest filed 2026-09-22). 13F is disclosed up to 45 days after quarter-end, so the most recent quarter fills in over the following weeks.
How the tape is positioned
84 tracked funds added or opened MIAX while 67 trimmed or exited it between 2026-Q1 and 2026-Q2 — the tape is split. When large holders disagree on a name, the funds moving first are sometimes ahead of the story.
A prompt to read the filings, not a verdict. 13F is a quarter-end snapshot disclosed up to 45 days late; a fund adds or exits for mandate, benchmark, and timing reasons that have nothing to do with a view on the stock. This is a starting question, not a signal to trade.
Conviction spread
MIAX’s largest tracked holder by dollar value, HORIZON KINETICS ASSET MANAGEMENT LLC, sizes it at 3.3% of its own reported 13F book, while the median holder sizes it at 0.0% of theirs — a 3.3pp conviction gap — its largest holder concentrates the name more heavily than the typical one.
Book-share is each fund’s reported value in MIAX divided by its whole reported 13F book, so it is comparable across funds of different sizes and is unaffected by stock splits. A higher share means a fund has committed more of its book to the name — a starting question about conviction, not a verdict or a signal to trade.
Institutional & insider positioning
Between 2026-Q1 and 2026-Q2, across 196 tracked filers holding MIAX, 133 increased or opened the position and 99 reduced or closed it; over the same quarter, open-market insider Form 4s were net sales.
This fuses two public signals for the same quarter — how tracked institutions changed their positions and whether insiders bought or sold in the open market. It describes what was filed; it is a starting question, not a verdict or a signal to trade.
New buyers & exits
Funds opening or closing a position in MIAX between the 2026-Q1 and 2026-Q2 13F filings, and the largest changes among funds holding it in both. New buyers and exits are counted on fund presence (split-invariant); adds and trims are measured on reported value.
New buyers 27
- J Digital 6 LLC$67M
- BALYASNY ASSET MANAGEMENT L.P.$63M
- WESTFIELD CAPITAL MANAGEMENT CO LP$26M
- NewEdge Advisors, LLC$25M
- Assenagon Asset Management S.A.$11M
- Langdon Equity Partners$10M
Full exits 32
- T. Rowe Price Investment Management, Inc.$161M
- CITADEL ADVISORS LLC$63M
- LORD, ABBETT & CO. LLC$33M
- Penn Capital Management Company, LLC$11M
- RENAISSANCE TECHNOLOGIES LLC$11M
- Woodline Partners LP$10M
Largest adds
- HORIZON KINETICS ASSET MANAGEMENT LLC$157M
- BlackRock, Inc.$102M
- VANGUARD PORTFOLIO MANAGEMENT LLC$87M
- VANGUARD CAPITAL MANAGEMENT LLC$63M
- BLAIR WILLIAM & CO/IL$40M
- HEALTHCARE OF ONTARIO PENSION PLAN TRUST FUND$29M
Largest trims
- North Reef Capital Management LP$30M
- Alyeska Investment Group, L.P.$25M
- Ghisallo Capital Management LLC$20M
- MILLENNIUM MANAGEMENT LLC$13M
- Allspring Global Investments Holdings, LLC$10M
- MORGAN STANLEY$9M
Institutional holders
One row per tracked fund, most shares held first (every row is from one quarter; reported value breaks ties). “% of value” is the fund’s share of this security’s tracked institutional value — not of shares outstanding.
| Fund | Shares | Reported value | % of value | Quarter |
|---|---|---|---|---|
| HORIZON KINETICS ASSET MANAGEMENT LLC added | 7,842,173 | $291M | 12.2% | 2026-Q2 |
| BlackRock, Inc. added | 5,071,754 | $188M | 7.9% | 2026-Q2 |
| VANGUARD PORTFOLIO MANAGEMENT LLC added | 3,786,418 | $141M | 5.9% | 2026-Q2 |
| SUSQUEHANNA INTERNATIONAL GROUP, LLP added | 3,355,043 | $125M | 5.2% | 2026-Q2 |
| VANGUARD CAPITAL MANAGEMENT LLC added | 3,165,686 | $118M | 4.9% | 2026-Q2 |
| Invesco Ltd. added | 2,020,650 | $75M | 3.2% | 2026-Q2 |
| J Digital 6 LLC new | 1,807,234 | $67M | 2.8% | 2026-Q2 |
| BLAIR WILLIAM & CO/IL added | 1,769,432 | $66M | 2.8% | 2026-Q2 |
| BALYASNY ASSET MANAGEMENT L.P. new | 1,682,924 | $63M | 2.6% | 2026-Q2 |
| AMERICAN CENTURY COMPANIES INC added | 1,587,196 | $59M | 2.5% | 2026-Q2 |
| STATE STREET CORP added | 1,432,894 | $53M | 2.2% | 2026-Q2 |
| JPMORGAN CHASE & CO added | 1,427,881 | $53M | 2.2% | 2026-Q2 |
| GEODE CAPITAL MANAGEMENT, LLC added | 1,395,680 | $52M | 2.2% | 2026-Q2 |
| ADAGE CAPITAL PARTNERS GP, L.L.C. trimmed | 1,143,920 | $43M | 1.8% | 2026-Q2 |
| HEALTHCARE OF ONTARIO PENSION PLAN TRUST FUND added | 1,039,449 | $39M | 1.6% | 2026-Q2 |
| MORGAN STANLEY trimmed | 950,593 | $35M | 1.5% | 2026-Q2 |
| TWO SIGMA INVESTMENTS, LP trimmed | 888,109 | $33M | 1.4% | 2026-Q2 |
| Allspring Global Investments Holdings, LLC trimmed | 857,682 | $33M | 1.4% | 2026-Q2 |
| BANK OF AMERICA CORP /DE/ trimmed | 856,980 | $32M | 1.3% | 2026-Q2 |
| Alyeska Investment Group, L.P. trimmed | 848,750 | $32M | 1.3% | 2026-Q2 |
| PRICE T ROWE ASSOCIATES INC /MD/ added | 844,464 | $31M | 1.3% | 2026-Q2 |
| FRANKLIN RESOURCES INC added | 784,799 | $29M | 1.2% | 2026-Q2 |
| Walleye Capital LLC added | 728,034 | $27M | 1.1% | 2026-Q2 |
| WESTFIELD CAPITAL MANAGEMENT CO LP new | 700,741 | $26M | 1.1% | 2026-Q2 |
| NewEdge Advisors, LLC new | 681,610 | $25M | 1.1% | 2026-Q2 |
| Nuveen, LLC added | 668,115 | $25M | 1.0% | 2026-Q2 |
| Caldwell Investment Management Ltd. trimmed | 600,000 | $22M | 0.9% | 2026-Q2 |
| UBS Group AG added | 567,797 | $21M | 0.9% | 2026-Q2 |
| Driehaus Capital Management LLC added | 566,052 | $21M | 0.9% | 2026-Q2 |
| NORTHERN TRUST CORP added | 562,337 | $21M | 0.9% | 2026-Q2 |
| AMERIPRISE FINANCIAL INC added | 559,485 | $21M | 0.9% | 2026-Q2 |
| SEVEN GRAND MANAGERS, LLC | 550,000 | $20M | 0.9% | 2026-Q2 |
| Ghisallo Capital Management LLC trimmed | 500,000 | $19M | 0.8% | 2026-Q2 |
| Clearstead Advisors, LLC trimmed | 473,937 | $18M | 0.7% | 2026-Q2 |
| ROYCE & ASSOCIATES LP added | 452,813 | $17M | 0.7% | 2026-Q2 |
| VICTORY CAPITAL MANAGEMENT INC added | 427,425 | $16M | 0.7% | 2026-Q2 |
| MASSACHUSETTS FINANCIAL SERVICES CO /MA/ added | 406,274 | $15M | 0.6% | 2026-Q2 |
| GOLDMAN SACHS GROUP INC trimmed | 399,844 | $15M | 0.6% | 2026-Q2 |
| BNP PARIBAS FINANCIAL MARKETS trimmed | 394,688 | $15M | 0.6% | 2026-Q2 |
| CHARLES SCHWAB INVESTMENT MANAGEMENT INC added | 373,541 | $14M | 0.6% | 2026-Q2 |
| D. E. Shaw & Co., Inc. added | 355,528 | $13M | 0.6% | 2026-Q2 |
| TOCQUEVILLE ASSET MANAGEMENT L.P. added | 338,225 | $13M | 0.5% | 2026-Q2 |
| VANGUARD FIDUCIARY TRUST CO added | 315,336 | $12M | 0.5% | 2026-Q2 |
| SEI INVESTMENTS CO trimmed | 307,062 | $11M | 0.5% | 2026-Q2 |
| Assenagon Asset Management S.A. new | 297,832 | $11M | 0.5% | 2026-Q2 |
| BARCLAYS PLC added | 295,775 | $11M | 0.5% | 2026-Q2 |
| Burkehill Global Management, LP | 290,000 | $11M | 0.5% | 2026-Q2 |
| MAD RIVER INVESTORS added | 289,000 | $11M | 0.5% | 2026-Q2 |
| MARSHALL WACE, LLP added | 287,480 | $11M | 0.4% | 2026-Q2 |
| Langdon Equity Partners new | 282,500 | $10M | 0.4% | 2026-Q2 |
| Nearwater Capital Markets, Ltd new | 279,000 | $10M | 0.4% | 2026-Q2 |
| JENNISON ASSOCIATES LLC new | 267,303 | $10M | 0.4% | 2026-Q2 |
| WELLINGTON MANAGEMENT GROUP LLP trimmed | 262,170 | $10M | 0.4% | 2026-Q2 |
| Caprock Group, LLC added | 259,873 | $10M | 0.4% | 2026-Q2 |
| North Reef Capital Management LP trimmed | 251,354 | $9M | 0.4% | 2026-Q2 |
| NORGES BANK trimmed | 237,900 | $9M | 0.4% | 2026-Q2 |
| York GP, Ltd. new | 230,729 | $9M | 0.4% | 2026-Q2 |
| FEDERATED HERMES, INC. added | 224,410 | $8M | 0.3% | 2026-Q2 |
| Philadelphia Financial Management of San Francisco, LLC new | 223,715 | $8M | 0.3% | 2026-Q2 |
| Bank of New York Mellon Corp added | 220,387 | $8M | 0.3% | 2026-Q2 |
| Schonfeld Strategic Advisors LLC added | 200,181 | $7M | 0.3% | 2026-Q2 |
| BlueCrest Capital Management Ltd new | 200,000 | $7M | 0.3% | 2026-Q2 |
| Hudson Bay Capital Management LP added | 190,223 | $7M | 0.3% | 2026-Q2 |
| MILLENNIUM MANAGEMENT LLC trimmed | 189,105 | $7M | 0.3% | 2026-Q2 |
| Coastal Bridge Advisors, LLC added | 183,761 | $7M | 0.3% | 2026-Q2 |
| MANUFACTURERS LIFE INSURANCE COMPANY, THE added | 177,273 | $7M | 0.3% | 2026-Q2 |
| XTX Topco Ltd added | 170,856 | $6M | 0.3% | 2026-Q2 |
| WELLS FARGO & COMPANY/MN added | 164,132 | $6M | 0.3% | 2026-Q2 |
| OSAIC HOLDINGS, INC. added | 157,902 | $6M | 0.2% | 2026-Q2 |
| Optiver Holding B.V. added | 152,285 | $6M | 0.2% | 2026-Q2 |
| NORTHWESTERN MUTUAL WEALTH MANAGEMENT CO new | 151,179 | $6M | 0.2% | 2026-Q2 |
| Sone Capital Management, LLC new | 138,903 | $5M | 0.2% | 2026-Q2 |
| HMV Wealth Advisors, LLC added | 137,957 | $5M | 0.2% | 2026-Q2 |
| Focus Partners Advisor Solutions, LLC added | 136,736 | $5M | 0.2% | 2026-Q2 |
| FJ Capital Management LLC new | 119,299 | $4M | 0.2% | 2026-Q2 |
| Moors & Cabot, Inc. added | 118,904 | $4M | 0.2% | 2026-Q2 |
| One Charles Private Wealth Services, LLC new | 118,419 | $4M | 0.2% | 2026-Q2 |
| RAYMOND JAMES FINANCIAL INC trimmed | 116,413 | $4M | 0.2% | 2026-Q2 |
| TD Asset Management Inc added | 109,708 | $4M | 0.2% | 2026-Q2 |
| Delta Global Management LP trimmed | 109,665 | $4M | 0.2% | 2026-Q2 |
| INTRINSIC EDGE CAPITAL MANAGEMENT LLC trimmed | 106,019 | $4M | 0.2% | 2026-Q2 |
| Qube Research & Technologies Ltd added | 101,105 | $4M | 0.2% | 2026-Q2 |
| RHUMBLINE ADVISERS added | 89,668 | $3M | 0.1% | 2026-Q2 |
| ALLIANCEBERNSTEIN L.P. added | 89,200 | $3M | 0.1% | 2026-Q2 |
| G2 Investment Partners Management LLC added | 85,000 | $3M | 0.1% | 2026-Q2 |
| Polar Capital Holdings Plc trimmed | 82,603 | $3M | 0.1% | 2026-Q2 |
| MBL Wealth, LLC trimmed | 78,902 | $3M | 0.1% | 2026-Q2 |
| CITIGROUP INC trimmed | 77,286 | $3M | 0.1% | 2026-Q2 |
| DEUTSCHE BANK AG\ added | 75,052 | $3M | 0.1% | 2026-Q2 |
| SPIREPOINT PRIVATE CLIENT, LLC | 68,883 | $3M | 0.1% | 2026-Q2 |
| ARROWSTREET CAPITAL, LIMITED PARTNERSHIP trimmed | 63,344 | $2M | 0.1% | 2026-Q2 |
| Voleon Capital Management LP added | 58,234 | $2M | 0.1% | 2026-Q2 |
| EagleClaw Capital Managment, LLC new | 57,800 | $2M | 0.1% | 2026-Q2 |
| ROYAL BANK OF CANADA added | 53,256 | $2M | 0.1% | 2026-Q2 |
| CREDIT AGRICOLE S A | 51,002 | $2M | 0.1% | 2026-Q2 |
| Atlas Brown,Inc. trimmed | 44,906 | $2M | 0.1% | 2026-Q2 |
| MetLife Investment Management, LLC added | 44,772 | $2M | 0.1% | 2026-Q2 |
| CANADA PENSION PLAN INVESTMENT BOARD new | 44,500 | $2M | 0.1% | 2026-Q2 |
| LPL Financial LLC added | 43,837 | $2M | 0.1% | 2026-Q2 |
| TWINBEECH CAPITAL LP new | 42,572 | $2M | 0.1% | 2026-Q2 |
Ownership over time
Tracked institutional holder count and total shares held by filing quarter (independent scales). The curated-era tail and any mid-ingest latest quarter are handled honestly — a partial quarter is not drawn as a collapse.
Reading this table
Funds hold the same stock for different reasons — an index fund “holds” almost everything, an active manager sizes a name to a mandate and a benchmark, and each fund entered at its own price and time. Because 13F is filed up to 45 days after quarter-end, every row is a backward-looking snapshot; a manager may have traded since. Share-class siblings (a company’s A and C shares) are rolled up to one line so a dual-class name is never double-counted. Compare like-for-like. A large holder is not an endorsement, and a fund exiting is not a warning — this is a starting question, not a verdict.
About 13F filings
A Form 13F is a quarterly disclosure that institutional investment managers with over $100 million in US-listed equities must file with the SEC. In plain English: it is a snapshot of the long stock positions a fund held at the end of a quarter. It covers long US-listed equities only — not short positions, options, cash, or private holdings — and the funds shown are the large sample we track, not the complete 13F universe.