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Types of Bonds

Basic Characteristics of a CMO Tranche

The cash flow from the CMO collateral may be allocated in a variety of ways. Usually, it is first allocated to meet the interest obligations on all tranches in the offering. Principal repayments, both scheduled and prepaid, are then distributed to the different classes of bondholders according to a predetermined priority schedule which is outlined in the CMO prospectus or offering circular. The tranche receiving principal repayment is referred to as “active” or “currently paying.” In more complex structures, more than one tranche can be paying principal at a time.

Each CMO tranche has an estimated first payment date, on which investors can expect to begin receiving principal payments, and an estimated last principal payment (or maturity) date, on which they can expect their final dollar of principal to be returned. The period before principal payments begin in the tranche, when investors receive interest-only payments, is known as the “lockout” period. The period during which principal repayments are expected to occur is called the “window.” Both first and last principal payment dates are estimates based on prepayment assumptions and can vary according to actual prepayments made on the underlying mortgage loans.


All information and opinions contained in this publication were produced by the Securities Industry and Financial Markets Association from our membership and other sources believed by the Association to be accurate and reliable. By providing this general information, the Securities Industry and Financial Markets Association makes neither a recommendation as to the appropriateness of investing in fixed-income securities nor is it providing any specific investment advice for any particular investor. Due to rapidly changing market conditions and the complexity of investment decisions, supplemental information and sources may be required to make informed investment decisions.