Speaking at the same event, Nobel laureate Joseph Stiglitz of Columbia University blamed U.S. and international regulators such as former Federal Reserve Chairman Alan Greenspan for failing to restrain an explosion in financial innovation and lending that led borrowers to rack up debt they couldn't repay. He criticized guidelines known as Basel II for encouraging too much self-regulation of banks.

``It was a massive failure of the brains of the economy,'' said Stiglitz. ``There was a party going on and the regulator with the same mindset of those in the party didn't want to be a party pooper.''