A Collateralized Debt Obligation (CDO) is a synthetic investment product that represents different loans bundled together and sold by the lender in the market. The holder of the collateralized debt obligation can, in theory, collect the borrowed amount from the original borrower at the end of the loan period.

Collateralized debt obligations (CDOs) are a type of structured investment finance product that contain various assets and loan products. Investment banks package bank loans, mortgages, and other assets into collateralized debt obligations—similar to funds—for institutional investors to buy.

A collateralized debt obligation is a complex structured finance product that is backed by a pool of loans and other assets. These underlying assets serve as collateral if the loan goes into default. The tranches of CDOs indicate the level of risk in the underlying loans, with senior tranches having the lowest risk.

CDOs are larger financial products that institutions then sell on a secondary market. Each CDO may include credit card debt, mortgages, auto loans and corporate debt. They are considered collateralized because borrowers have promised to repay the debt within each part of the CDO.