How 'one big lie' unravelled in a flash

US regulators never inspected Bernard Madoff's investment advisory business, alleged to be a Ponzi scheme that cost investors $50 billion, after he subjected it to oversight two years ago, people familiar with the case said.

The Securities and Exchange Commission hadn't examined Madoff's books since he registered the unit with the agency in September 2006, two people said, declining to be identified because the reviews aren't public. The SEC tries to inspect advisors at least every five years and to scrutinize newly registered firms in their first year, former agency officials and securities lawyers said.