What is the meaning of Collateralized Mortgage Obligation?

Collateralized Mortgage Obligation is a complex bond structure which reallocates interest and principal payment streams. These tranches, which are often designated as A to Z pieces or securities, are engineered from mortgage backed securities used as the underlying collateral. Collateralized Mortgage Obligations come in many shapes and sizes and are often viewed as unique constructions. Some of the more commonly named tranches are: Interest Only, Principal Only, Floater, Inverse Floater, Planned Amortization Class, Support, Scheduled, Sequential, Targeted Amortization Class, and Z or Accrual Bond. Often, many of these securities contain option characteristics. Related structures are Collateralized Bond Obligations and Collateralized Loan Obligations.