Banks are returning to a practice they abandoned after the financial crisis: taking Americans' credit-card debt, slicing and dicing it, and selling it off as bonds. So far this year, banks and other companies that issue credit cards have sold $21 billion in bonds backed by those accounts' debt, Bloomberg News reported on Aug 29 -- up from $4.8 billion in the same period the year prior. Broadly, it's a bet that consumers have their finances in order and will continue to be able to pay their monthly bills on time. Card issuers have cut off their least creditworthy customers, and reforms such as the CARD Act have forced them to be more careful about the riskiness of new customers. While all of this has put a crimp in credit-card companies' growth, it has made for fat, steady revenue streams.