Former Federal Reserve Chairman Alan Greenspan, Former Treasury Secretary John Snow, and SEC Chairman Chris Cox testified about the state of the economy, recent turmoil in the U.S. and global financial markets, and the role of federal regulators in the breakdown of the market on Wall Street. In response to sometimes partisan and pointed questioning Mr. Greenspan said that he may have been mistaken about the reliability of some financial instruments, such as insurance-like credit-default swaps, that were not yet common when he expressed his views about markets being able to police themselves.