While investors still hanker for the days of 20%-plus returns on equity, trading operations are turning in far more pedestrian results. Credit Suisse on Thursday became the latest example. It posted a 9.7% return on equity in the second quarter as fixed-income trading results came in nearly 60% below the year-earlier period.

The trouble is, far lower returns simply may be a reversion to more normal levels. If that is so, you're talking about the normal that existed for banks in less bubbly times.