Average daily volume in August was essentially unchanged from the same month last year, according to data from BATS Global Markets.
The industry traded about 5.5 billion shares per day, on average, this month, up slightly from 5.4 billion shares in August 2012.
Among the eight major exchanges, Nasdaq remained at the top of the list in August, processing about 16 percent of all volume.
About 33 percent of all volume was traded off-board this month, according to BATS. That is down from 34 percent in August 2012.