Alex Blumberg and NPR correspondent (and "Planet Money" reporter) Dave Kestenbaum examine what went wrong with the credit ratings agencies. When all these financial instruments that brought down our economy—the mortgage backed securities, the derivatives—were originally issued, the rating agencies (Standard and Poors, Moody's and Fitch) gave many of these things their top rating of triple-A.

Alex Blumberg and Adam Davidson tackle a very tough subject: Trying to explain exactly what a bank is and does. They talk to a number of experts about what has gone wrong in banking, but not before bringing us all up to speed on some banking basics, like understanding a bank balance sheet, and a bank's assets and liabilities, and the squishy business of what banks say about their balance sheets compared to what they are.Alex and Adam walk us step by step through the complications of the US government buying up bad assets from banks, and explain why, when it comes to footing the bill, the government might just prefer to not be in charge of the very banks it is having taxpayers bailout.