Interactive Brokers shares jumped 35.3% in the first half of 2026, driven by rapid customer growth and expansion into new markets like South Korea. Total customer accounts grew 31% to 4.75 million in the first quarter, while commission revenue rose 19% and net interest income increased 17%. The company posted a 77% pre-tax margin, reflecting its high profitability. Shares now trade at a price-to-earnings ratio of 41, up from around 20 in prior years, as investors reward its consistent market share gains.
Interactive Brokers Group IncRapid customer growth (31% account increase) and market expansion into South Korea drive revenue and profitability.