. >> safer: janet tavakoli is an analyst specializing in derivatives, the exotic financial instruments the meltdown. she argues that the bad mortgage loans that fueled the crisis were repackaged by investment banks, sliced into increasingly complex derivatives, and resold to other investors, even though the underlying mortgages were often virtually worthless. >> you had various traders buying each other's products to artificially keep the prices up so that the bubble didn't collapse. >> safer: not only that, but the mortgage derivatives being traded were so mind-numbingly complicated, nobody understood them fully, certainly not the pigeons, the buyers at banks, mutual funds, pension funds and insurance companies who wound up holding a bag full of worthless paper. these guys are smart guys. they're all graduates of the finest business schools in the country, correct? >> yes. if they were gullible, they're sophisticated investors. so they can't really go back to the investment banks that sold them this product and say, "we've been had," because they held themselves out to be experts in t