Caldwell Loads Up On Miami International Holdings (MIAX) With 663,000 Shares in Q3 Buy

On October 27, 2025, Caldwell Investment Management Ltd. disclosed a new position in Miami International Holdings (NYSE:MIAX), acquiring 663,810 shares in a trade estimated at $27.06 million on September 30, 2025.

What happened

Caldwell Investment Management Ltd. initiated a new equity position in Miami International Holdings, according to its quarterly report filed with the U.S. Securities and Exchange Commission on October 27, 2025. The fund reported ownership of 663,810 shares valued at $27.06 million for Q3 2025, marking the firm's first reported stake in the exchange operator during the quarter ended September 30, 2025.

What else to know

This new position accounts for 17.76% of Caldwell’s 13F reportable assets under management for Q3 2025 and has become the fund's second-largest holding.

Top holdings after the filing:

• UNK:CBOE: $29.05 million (19.07% of AUM as of September 30, 2025)
• NYSE:MIAX: $27.06 million (17.76% of AUM as of September 30, 2025)
• NYSE:BAC: $18.34 million (12.04% of AUM as of September 30, 2025)
• NYSE:ICE: $16.79 million (11.02% of AUM as of September 30, 2025)
• NYSE:AEM: $9.79 million (6.43% of AUM as of September 30, 2025)

As of closing on October 27, 2025, Miami International Holdings is priced at $44.27 per share, up by 36.01% since its initial public offering on August 14, 2025.

Company Overview

Company Snapshot

Miami International Holdings operates multiple U.S. and international markets for options, futures, and equities, including MIAX Options, MIAX Pearl, MIAX Emerald, MIAX Sapphire, MIAX Pearl Equities, MIAX Futures, BSX, and TISE. It also provides clearing services and owns Dorman Trading, a full-service futures commission merchant.

The company serves institutional clients, professional traders, introducing brokers, and retail customers seeking access to multi-asset trading and clearing solutions.

Miami International Holdings is a diversified financial markets operator with a growing presence in options, futures, and equities trading. The company employs a multi-market strategy to capture trading volumes across asset classes.

Foolish take

Caldwell Investment Management made a significant buy in Miami International Holdings. The firm established a new position of more than 600,000 shares, making MIAX its second-largest holding at nearly 18% of its portfolio.

This is a big move for the institution, both in terms of the $27 million amount and the sizable position in its portfolio. Miami International Holdings held its initial public offering (IPO) just two months ago, and investing early after an IPO can be risky, as many stocks take time to find their footing after going public.

Since its IPO, MIAX has surged by more than 36%, as of October 27, 2025. Because it's such a new stock, though, it can be tough for investors to tell how much of its price and performance are rooted in hype versus substance.

While investing in IPOs isn't necessarily a bad move for everyday investors, it's important to keep a long-term outlook and ensure your portfolio is properly diversified. Miami International Holdings could be on track to become a blockbuster investment, but with only two months of performance data to examine, investors may want to stay cautiously optimistic for now.

Glossary

13F reportable assets: Assets disclosed by institutional investment managers in quarterly SEC Form 13F filings, showing certain U.S. equity holdings.
Assets under management (AUM): The total market value of investments managed on behalf of clients by a fund or firm.
Equity position: Ownership of shares in a company, representing a stake in that company.
Exchange operator: A company that owns and manages one or more financial markets where securities, derivatives, or other assets are traded.
Futures commission merchant: A firm or individual that solicits or accepts orders to buy or sell futures contracts and accepts money or property from customers to support such orders.
Clearing services: Processes that ensure trades are settled, including transferring securities and funds between buyers and sellers.
Introducing broker: A broker who brings clients to a larger brokerage firm but does not handle the actual execution or clearing of trades.
Multi-asset trading: Trading that involves multiple types of financial instruments, such as stocks, options, and futures, within one platform or strategy.
Multi-market strategy: An approach where a company operates across several trading venues or exchanges to capture more trading activity.
Institutional clients: Organizations such as pension funds, mutual funds, or insurance companies that invest large sums of money.
Stake: The amount of ownership or interest an investor holds in a company or asset.
TTM: The 12-month period ending with the most recent quarterly report.

Bank of America is an advertising partner of Motley Fool Money. Katie Brockman has no position in any of the stocks mentioned. The Motley Fool recommends Cboe Global Markets and Intercontinental Exchange. The Motley Fool has a disclosure policy.