Moody's credit rating agency downgraded the credit of fifteen of the country's biggest banks Thursday, including Bank of America, Citigroup, Goldman Sachs, and JP Morgan Chase. Moody's cited the complexity and opacity in investment practices, and also problems with risk management. For example, JP Morgan Chase announced last month that they lost $5 billion on bets they made tied to corporate bonds.

A lower credit rating could mean company's limit their businesses with some of these banks, and the costs banks then incur could be passed on to consumers.