Some investors no doubt took a summer vacation in July, but the market's meltdown may also have cooled interest in stock trading.

E*Trade Financial

(ET) - Get Report

Wednesday said daily average revenue trades fell 1.6% to 106,623 from 108,344 in June. The biggest decline was in the U.S. retail segment, which fell 3.2%. International trading rose 6.5%.

"July retail volumes were affected by traditional seasonality," the company said. "In this type of market, we continue to benefit from diversification within brokerage, where we experienced relative strength in our international and professional segments."

Margin debt balances increased 1.1% from June to $2.09 billion.

Last week,


(AMTD) - Get Report

also reported a slight decline in July.

Charles Schwab


, the biggest U.S. discount brokerage, said trading rose slightly. The firm recently slashed trading commission fees.