(1) A multi-tranche security with credit risk exposure to corporations. A securitization of corporate obligations. CDOs can be securitizations or re-securitizations of commercial loans, corporate bonds, other types of ABSs, residential MBSs, commercial MBSs, and emerging market debt. CDOs may even be backed by other CDOs. Securitizations of corporate bonds are a type of CDO called a collateralized bond obligation or CBO. A synthetic CDO uses credit default swaps rather than actual corporate obligations to create a pool of credit exposure. Similar to the more familiar CMO, except that in a CDO the tiers or tranches are created with differing levels of credit quality. A CBO divides the credit risk of a pool of high yield bonds into different classes that appeal to investors with different credit risk tolerances. The CDO structure creates at least one tier of investment-grade bonds. The contractual rules for the cash flow distributions in a CDO structure enable the senior tranches to receive high credit ratings by shifting risk to the equity tranche. See equity tranche, special purpose vehicle, and waterfall.

(2) The term "CDO" may be used to refer to the special purpose entity, SPV, that holds the securitized assets.