Miami International Holdings, Inc. (MIAX) Institutional Ownership

Ownership Summary

Miami International Holdings, Inc. (NYSE:MIAX) showed up in the 13F filings of 161 institutional investors as of December 2025.

• They owned 54.5% of outstanding stock in December 2025, up from 37.9% the prior quarter.
• Their total shares held in MIAX increased 50.73% from the prior quarter, while the number of investors in Miami International Holdings stayed flat year over year.
• Among the 161 funds, 128 bought more Miami International Holdings shares, 22 sold down, and 11 held their ground.
• Altogether, these fund groups held 38.21Mn shares in MIAX by December 2025, up by 12.86Mn shares quarter on quarter, and with no net change year over year.
• As of December 31, 2025, T. Rowe Price Investment Management, Inc. held the largest stake in Miami International Holdings with 4.15Mn shares, accounting for 5.91% of total shares outstanding.
• The most significant purchases of MIAX for the quarter ending December 2025 came from HORIZON KINETICS ASSET MANAGEMENT LLC (1.63Mn), VANGUARD CAPITAL MANAGEMENT LLC (1.41Mn), VANGUARD PORTFOLIO MANAGEMENT LLC (1.37Mn), CITADEL ADVISORS LLC (988.2K), Morgan Stanley (926.08K).
• The largest sales of MIAX for the quarter ending December 2025 came from Goldman Sachs Group Inc (735.02K), Delta Global Management LP (270.4K), Jump Financial, LLC (266.3K), North Reef Capital Management LP (250.73K), AMERICAN CENTURY COMPANIES INC (226.81K).
• Business Quant data shows the 10 biggest positions in Miami International Holdings as of December 2025 are held by T. Rowe Price Investment Management, Inc. (4.15Mn), HORIZON KINETICS ASSET MANAGEMENT LLC (3.45Mn), SUSQUEHANNA INTERNATIONAL GROUP, LLP (3.3Mn), BlackRock, Inc. (2.23Mn), CITADEL ADVISORS LLC (1.61Mn), Invesco Ltd. (1.59Mn), Alyeska Investment Group, L.P. (1.45Mn), VANGUARD CAPITAL MANAGEMENT LLC (1.41Mn), VANGUARD PORTFOLIO MANAGEMENT LLC (1.37Mn), ADAGE CAPITAL PARTNERS GP, L.L.C. (1.25Mn).