Among economics experts it is well known that CDO's are at the root of the economic collapse in the US, if not the major cause... 1) What I want to know, is WHY were they allowed to be sold? 2) Secondly, why isn't the fact that they were *illegally upgraded from BBB risk, to AAA, and sold as a no risk investment being told to the now vulnerable American public? Why is it being hidden? For those of you that aren't familar with the CDO, here is an Answers.com definition of it: Collateralized Debt Obligation - CDO An investment-grade security backed by a pool of bonds, loans and other assets. CDOs do not specialize in one type of debt but are often sub prime mortgages, loans, or debt. Investopedia Says: Similar in structure to a collateralized mortgage obligation (CMO) or collateralized bond obligation (CBO), CDOs are unique in that they represent different types of debt and credit risk. In the case of CDOs, these different types of debt are often referred to as 'tranches' or 'slices'. Each slice has a different maturity and risk associated with it. The higher the risk, the more the CDO pays.