One of the world's leading experts on credit derivatives (financial instruments that transfer credit risk from one party to another), Das is the author of a 4,200-page reference work on the subject, among a half-dozen tomes... Das is pretty droll for a math whiz, but his message is dead serious. He thinks we're on the verge of a bear market of epic proportions... The cause: Massive levels of debt underlying the world economic system are about to unwind in a profound and persistent way. He's not sure if it will play out like the 13-year decline of 90% in Japan...