An abbreviated form for constant maturity treasury rate; an interest rate benchmark that provides the yield of a synthetic security that is interpolated from the Treasury yield curve for a given maturity. The yield (on nominal Treasury rates) is adjusted to constant maturities. This rate represents the par yield for a treasury instrument that matures in a given maturity (1, 2, 3, 5, 7, 10, 20, or 30 years).
There are derivatives in which the underlying rate is CMT rate: these include CMT swaps, CMT options, CMS-CMT basis swaps, etc.
