How do CDOs work?
Initially, all the cash flows from a CDO’s collection of assets are pooled together. This pool of payments is separated into rated tranches. Each tranche also has a perceived (or stated) debt rating to it. The highest end of the credit spectrum is usually the ‘AAA’ rated senior tranche. The middle tranches are generally referred to as mezzanine tranches and generally carry ‘AA’ to ‘BB’ ratings and the lowest junk or unrated tranches are called the equity tranches. Each specific rating determines how much principal and interest each tranche receives. (Keep reading about tranches in Profit From Mortgage Debt With MBS and What is a tranche?) The ‘AAA’-rated senior tranche is generally the first to absorb cash flows and the last to absorb mortgage defaults or missed payments. As such, it has the most predictable cash flow and is usually deemed to carry the lowest risk. On the other hand, the lowest rated tranches usually only receive principal and interest payments after all other tranches
