Interactive Brokers' Q3 2026 net interest income, due for release after market close on October 15, will likely reflect continued expansion in client margin loans and credit balances amid a higher average interest-earning asset base estimated near $240 billion. Margin loans rose 36% year over year to $105.2 billion by September, while credit balances grew 20%, supporting interest income even as the Fed funds target range sits at 3.75–4.00% following the September hike. This growth has driven sequential increases, with Q2 net interest income reaching $1.06 billion versus $967 million in Q3 2025. Traders monitor balance-sheet momentum and any rate-path signals, as each 25-basis-point Fed move historically shifts annual net interest income by roughly $81 million. Strong customer equity and DARTs add context for the interest-earning asset trajectory.