Schwab said total client assets were $1.003 trillion at the end of August, up 43% from a year earlier.
The discount broker gained nearly $10 billion in net new assets in August.
August trading was the slowest of the year, with daily trading activity down 15% from a month earlier.
However, the average daily trading volume of 184,600 shares was 46% higher than a year ago.
September trading volumes are up somewhat, to about 215,000 shares a day according to Schwab.