"If you're not fearful, you're crazy."

JAMIE DIMON, JPMorgan Chase's chief executive, on the fear factor among credit card lending

Are credit cards the next collapse?

First came trouble with mortgages, then home equity loans and commercial real estate. Now, banks are starting to worry about credit cards.

As the economy slows and unemployment rises, consumers are defaulting on credit-card payments more often. And though that trend is unlikely to create a crisis in line with the mortgage fallout, it's still a headache for banks that are already hurting.

U.S. banks charged off 5.47 percent of all credit card loans in the second quarter, according to the Federal Reserve, representing some $50 billion that they'll likely never collect. That's up from 3.85 percent the year before, and that is a movement that's on the radar of Ken Lewis, chief executive of Charlotte's Bank of America Corp.

Asked in a recent TV interview if credit-card debt would be “the next shoe to drop” for the banking industry, Lewis replied: "It, in some ways, already is," adding that such losses have risen "pretty substantially."