Interactive Brokers margin loans climbed to $108.5 billion at the end of June 2026, up 67% from a year earlier, driving second-quarter net revenue 28% higher to $1.90 billion. The headline growth looks strong; the mechanism behind it is more nuanced.
Customer accounts rose 34% to 5.19 million over the same period, and customer equity grew 40% to $930.3 billion. Margin loans (balances customers borrow against their portfolios to buy more securities) grew nearly twice as fast as equity, pushing the ratio of margin loans to customer equity to 11.7%, the highest point in FM Intelligence’s ten-quarter analysis.
Interactive Brokers Margin Loans and the NIM Squeeze
Net interest income rose 23% to $1.06 billion, but net interest margin (the spread between what the firm earns on assets and pays on liabilities) fell to 1.93% from 2.07% a year earlier. That was a sixth consecutive year-on-year decline, with the yield on margin loans dropping to 4.10%.
The picture is clearer when you look at average balances. Average customer margin loans for Q2 2026 were $96.6 billion, compared with $60.9 billion in Q2 2025, according to the company’s Q2 2026 earnings release. Average total interest-earning assets rose to $228.6 billion from $166.6 billion. The book grew; the margin on that book shrank.
The NIM compression was already visible a quarter earlier. In Q4 2025, Interactive Brokers reported a net interest margin of 2.02%, with the annualised yield on margin loans at 4.39%, both figures down from the prior year, according to the Q4 2025 earnings release. The direction of travel has been consistent.
Customer credit balances (cash held on account by clients) rose 27% year-on-year to $182.4 billion, another sign of a larger balance sheet rather than improved yields.
What Rate Moves Mean for Full-Year Income
FM Intelligence models 2026 full-year net interest income in a range of $3.95 billion to $4.30 billion, with a base case near $4.15 billion. The scenarios hinge on two things: how quickly customer balances grow and which way US dollar rates move.
On rate sensitivity, the snippet cites $82 million of annual net interest income per 0.25-percentage-point move in US dollar rates. Interactive Brokers’ 10-K filed with the SEC for the year ending 31 December 2025 shows a figure of $77 million per 0.25-point move, based on customer balances at that date. The difference likely reflects the higher balances carried into mid-2026; both figures point in the same direction. FM Intelligence uses $82 million in its Q2-based modelling.
Rate expectations have also shifted. For much of 2025, markets priced in cuts; the working assumption now is a hold or a modest rise. That matters more for Interactive Brokers than for most brokers, given the scale of its interest-earning balance sheet.
Beyond interest income, commissions rose 27% year-on-year to $673 million in Q2 2026, up from $516 million in Q2 2025. Total daily average revenue trades (DARTs, the industry measure of chargeable trading activity) rose 36% to 4,824 thousand, though annualised cleared DARTs per account were essentially flat at 207 versus 206 a year earlier. Volume grew with the client base, not because existing clients traded more.
GAAP diluted earnings per share came in at $0.69 for the quarter, up from $0.51 in Q2 2025, with a pre-tax margin of 75%. The board declared a quarterly cash dividend of $0.0875 per share, payable on 14 September to shareholders of record as of 1 September, according to Yahoo Finance. Adjusted EPS of $0.69 beat the Zacks consensus of $0.64, representing an earnings surprise of 7.81%, as Zacks reported.
Paul Howard, senior director at digital-asset liquidity provider Wincent, argued that Interactive Brokers’ results confirm retail trading remains active across equities, commodities and derivatives, and that AI-driven tools are lowering the barrier to more complex products. He expects digital assets to take a larger share in the second half as investors rotate into markets that lagged the year’s rally. ‘I expect crypto trading volumes to once again exceed $100 billion during H2,’ Howard said. Retail order flow did rebound in June, though crypto trailed that move.
For investors holding IBKR shares, the key question for the rest of 2026 is whether balance-sheet growth can keep compounding. If the Fed holds rates steady and margin loan demand stays strong, the FM Intelligence base case of $4.15 billion in full-year net interest income looks achievable. A rate cut would reduce that by roughly $82 million for each 0.25-point move; a rise would add the same. The next Federal Reserve (Fed) decision is the trigger to watch.
