In the Wall St. Journal (via delong):
Mr. Rajan, a professor at the University of Chicago's Booth Graduate School of Business, chose that moment to deliver a paper called “Has Financial Development Made the World Riskier?”
His answer: Yes.
He says he had planned to write about how financial developments during Mr. Greenspan's 18-year tenure made the world safer. But the more he looked, the less he believed that. In the end, with Mr. Greenspan watching from the audience, he argued that disaster might loom.
Incentives were horribly skewed in the financial sector, with workers reaping rich rewards for making money, but being only lightly penalized for losses, Mr. Rajan argued. That encouraged financial firms to invest in complex products with potentially big payoffs, which could on occasion fail spectacularly.
He pointed to “credit-default swaps,” which act as insurance against bond defaults. He said insurers and others were generating big returns selling these swaps with the appearance of taking on little risk, even though the pain could be immense if defaults actually occurred.
Mr. Rajan also argued that because banks were holding a portion of the credit securities they created on their books, if those securities ran into trouble, the banking system itself would be at risk. Banks would lose confidence in one another, he said: “The interbank market could freeze up, and one could well have a full-blown financial crisis.”
Two years later, that's essentially what happened.