Why Interactive Brokers Stock Zoomed 35.3% Higher In The First Half of 2026

Shares of Interactive Brokers (NASDAQ: IBKR) jumped a solid 35.3% in the first half of 2026, according to data from S&P Global Market Intelligence. The financial markets brokerage is growing like a weed and benefiting from increased interest from traders in international markets such as South Korea.

More customers trading on Interactive Brokers -- otherwise known as IBKR -- means steadily growing revenue. Here's why the stock was soaring yet again in the first half of 2026, and what the future may hold for this stock market winner.

Fast customer growth, benefiting from the bull market

One of the pitches IBKR makes to customers is the ability to trade most international markets from most countries worldwide. It takes a long time to set up direct market connections outside the United States, meaning competing brokerages do not offer this type of access to customers. Earlier this year, IBKR launched a direct connection to the South Korean market, giving its customers around the world a direct way to invest in the country's booming stocks.

It is these types of customer value propositions that have driven IBKR's market share gains in recent years, and 2026 is no exception. In the first quarter of 2026, total customer accounts grew by 31% to 4.75 million, a strong leading indicator of future trading revenue. Commission revenue grew by 19% year-over-year last quarter, driven by stocks, options, and cryptocurrencies, while net interest income was up 17%.

Importantly, IBKR has one of the highest profit margins of any business in the world, posting a 77% pre-tax margin in the first quarter. With the business firing on all cylinders due to the strong growth in accounts, revenue, and bottom-line profitability, investors keep sending the stock higher. It is now up almost 500% in the last five years alone, generating tremendous gains for long-term shareholders.

Image source: Getty Images.

Should you buy Interactive Brokers stock?

Part of IBKR's gains have come from an increase in its earnings multiple. Shares now trade at a price-to-earnings ratio (P/E) of 41 compared to closer to 20 in 2022, 2023, and 2024. This elevated earnings multiple is unsurprising because of IBKR's long history of customer account acquisition in global financial asset trading.

This does not neccesarily mean the stock is a screaming buy today, after going up 35% this year and 500% in the last five. Investors who buy today should not expect this same level of stock price appreciation over the next five years, although over the long run, if IBKR keeps up this earnings growth, it will lead to solid stock returns.

Brett Schafer has positions in Interactive Brokers Group. The Motley Fool has positions in and recommends Interactive Brokers Group. The Motley Fool recommends the following options: long January 2027 $43.75 calls on Interactive Brokers Group and short January 2027 $46.25 calls on Interactive Brokers Group. The Motley Fool has a disclosure policy.