Still, one could argue--and many did--that Greenspan, at least, had no business being quite so shocked. Over the years, countless people had challenged his deregulatory dogma, including (to name just a few) Joseph Stiglitz and Paul Krugman, both Nobel Prize-winning economists, and Brooksley Born, who was head of the Commodity Futures Trading Commission from 1996 to 1999. Born eventually became something of a Cassandra figure for the crisis, since she repeatedly called for regulating the market for derivatives, those ultracomplex financial products that eventually helped bring down the economy. Those calls were silenced when Greenspan, along with then-Treasury Secretary Robert Rubin and then-Securities and Exchange Commission Chair Arthur Levitt, took the extraordinary step of convincing Congress to pass legislation forbidding Born's agency from taking any action for the duration of her term.