Securitization has spanned the creation of a plethora of exotic and increasingly complex financial instruments "engineered" from the payment streams thrown off by MBS's. The most prevalent of these new classes of engineered financial assets are known as collateralized debt obligations (CDOs). A CDO is created when a government-sponsored entity or Wall Street investment bank buys up a large pool of prime, near prime,or subprime mortgages to be securitized. Payment streams are then carved up and distributed to various "tranches" distinguished according to their level of exposure to losses from defaults occurring in the underlying mortgage pool. Our expertise goes back to participation, in the design of the first commercial mortgage backed security in the 1980's and in the early 1990's.