CMOs are considered a relatively safe investment. Most are “agency CMOs” because they are guaranteed by government entities, such as Ginnie Mae, Fannie Mae, or Freddie Mac. Credit safety. “Non-agency CMOs” are the sole responsibility of the issuer, meaning they are not backed by the government.

A collateralized debt obligation (CDO) is a complex structured finance product that is backed by a pool of loans and other assets and sold to institutional investors. A CDO is a particular type of derivative because, as its name implies, its value is derived from another underlying asset.

Typically, retail investors can't buy a CDO directly. Instead, they're purchased by insurance companies, banks, pension funds, investment managers, investment banks, and hedge funds. These institutions look to outperform the interest paid from bonds, such as Treasury yields.

A collateralized mortgage obligation (CMO) refers to a type of mortgage-backed security that contains a pool of mortgages bundled together and sold as an investment. Organized by maturity and level of risk, CMOs receive cash flows as borrowers repay the mortgages that act as collateral on these securities.