Interactive Brokers’ customer accounts jump 34% as rate hike adds to interest income

Interactive Brokers Group reported second-quarter 2026 earnings of $0.69 per diluted share on net revenues of $1.90 billion, alongside continued rapid growth in its client base. Customer accounts rose 34% year-over-year to 5.19 million, while customer equity — the total value of assets held across all client accounts — climbed 40% to $930.3 billion.

That combination of account growth and rising average account size points to a brokerage adding both new, generally smaller retail accounts and retaining higher-balance clients whose portfolios have appreciated, a pattern common across brokerages during periods of broad market gains. Interactive Brokers has built much of its growth around low-cost, high-volume trading infrastructure aimed at both retail investors and independent financial advisors and hedge funds that use its platform for execution.

A notable piece of the company’s disclosure was its sensitivity to interest rates: Interactive Brokers estimates that each quarter-point increase in U.S. dollar interest rates adds approximately $81 million to its annual net interest income. That figure matters because a meaningful share of brokerage revenue for firms like Interactive Brokers comes not from trading commissions but from the interest earned on customer cash balances and margin lending — a business line that becomes more profitable, not less, when rates rise, unlike many other financial businesses.

The Federal Reserve raised its target rate on September 16, 2026, giving the company’s interest-income sensitivity direct relevance to its near-term results. With customer equity approaching $1 trillion and account growth still running at a rate rarely seen among established brokerages, Interactive Brokers’ scale increasingly means that small changes in the fed funds rate translate into tens of millions of dollars in incremental annual revenue — a dynamic that has made the company’s results a closely watched proxy for how rate-sensitive, high-balance brokerage models perform through a shifting rate environment.