Interactive Brokers Group's second-quarter net revenue rose 28% to $1.90 billion, and most coverage focused on the headline growth. A FM Intelligence deep dive looks at how that growth was built, and finds a balance-sheet story rather than a rate story.

The full breakdown sits on the FM Intelligence DataLab portal, which traces where the activity actually came from over the past ten quarters.

Margin Loans Up 67% While Accounts Rose 34%

Customer margin loans reached $108.5 billion at the end of June, up 67% from a year earlier. That outpaced the 34% rise in customer accounts, to 5.19 million, and the 40% rise in customer equity, to $930.3 billion.

Borrowing per account rose about 24%, to roughly $20,900, and margin loans equalled 11.7% of customer equity, the highest reading in the period the analysis covers.

Net interest income rose 23% to $1.06 billion, yet net interest margin fell to 1.93% from 2.07%, a sixth straight year-over-year decline, as the yield on margin loans dropped to 4.10%. The growth came from a larger balance sheet, not higher rates. Interactive Brokers' headline results were covered separately by FinanceMagnates.com.

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What the Deep Dive Projects for the Second Half

Using the rate sensitivity Interactive Brokers discloses, about $82 million of annual net interest income for each 0.25 point move in US dollar rates, FM Intelligence models 2026 net interest income in a range of $3.95 billion to $4.30 billion, with a base case near $4.15 billion.

The scenarios turn on the rate path, which has shifted from the cuts assumed for much of 2025 toward a hold or a modest rise, and on how fast customer balances grow. The figures are FM Intelligence estimates, set out as base, bull and bear cases.

The Digital-Assets Read-Through

Broadening retail activity also points beyond equities. Paul Howard, senior director at digital-asset liquidity provider Wincent, said 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 role in the second half as investors rotate into markets that have lagged the year's rally.

"I expect crypto trading volumes to once again exceed $100 billion during H2," Howard said.

That call runs ahead of recent data: retail order flow rebounded in June while crypto trailed the move, as FinanceMagnates.com reported.

The full analysis, charts and scenario tables are on the FM Intelligence DataLab portal.