Interactive Brokers customers traded less per account as the account base grew

Customers are trading less per account

Interactive Brokers said in its results that customers made 168 commission-earning trades per account a year, annualised, in the September 2026 quarter. That compares with 207 in the quarter before and 195 a year ago, falls of 19% and 14%, as the release shows. The account count is why the ratio matters: accounts rose 35% on the year, so total trading has to grow about as fast for each account to stay as active as before.

Total trading did not keep pace. Daily average revenue trades, the count of commission-earning trades per day, were up 18% on the year but 11% below the quarter before.

Commission growth includes a passed-through fee

Commissions were $602 million, up 12% on a year ago. Within that may sit up to $30 million of regulatory fees that the company passes on to customers; none was charged a year earlier, and the chief financial officer said they do not affect profit. If all of it is booked in commissions, they rose about 6.5% without it, calculated from the reported figures, which would be slower than both trades and accounts.

The explanation covers one quarter's step, not the year

Chief executive Milan Galik pointed to the quarter before: "In the previous quarter, we probably benefited from some activity that was related to the IPO." He added that the listings expected this quarter had been delayed and that volatility should rise into the midterm elections. Asked whether the dip was concentrated in some customer segments, he answered "Broad-based."

The IPO point fits the step down from the quarter before. It speaks only to the step from the quarter before, so it does not by itself explain the fall against a year ago, and that comparison is the cleaner one because the earlier quarter was probably lifted by that activity. One reading is that newer accounts are smaller and trade less: customer equity per account was about $173,000, calculated, against $184,000 a year ago. Peterffy described recently acquired customers as higher-volume, so the call points the other way on trading, if not on balances. Another reading is that the ratio is diluted by a base that grew quickly while older accounts trade as before. The filed numbers do not separate the two.

Balances carry profit; September's rises reach income next

What held up is the interest side. Net interest income, the spread earned on customer loans and cash, was $1,154 million. Average customer margin loans were 47% higher than a year ago. Average Fed funds were 63 basis points lower than a year ago, yet margin loan interest rose 36% on higher balances. Because the Fed's rate rises came in mid-September, the chief financial officer said most of their effect will show in the fourth quarter. A Fed rate rise late in the quarter adds to this: the company estimates that a quarter-point move changes annual net interest income by $83 million.