Each Constant Maturity Treasury Index is based on the corresponding Treasury Yield Curve Rate* and is usually computed by averaging either the past week's or the past month's daily rates of the underlying Constant Maturity Treasury.

For example, the most popular and commonly known index is the Monthly 1-Year CMT. This index is based on the 1-Year Constant Maturity Treasury and changes once a month. The current rate is calculated by averaging the past month's daily rates of the 1-Year Constant Maturity Treasury.

* A set of theoretical securities with 'artificially constant' maturity, all priced at par, is constructed daily by the U.S. Treasury based on the rates of existing, marketable securities issued by the U.S. government.

These hypothetical 'constant maturity' securities are called 'Constant Maturity Treasuries', or CMTs. Yields on Treasury securities at 'constant maturity' are also known as Treasury Yield Curve Rates.

Our historical graph can help you to get an idea of how the eleven Constant Maturity Treasuries perform over interest rate cycles:

What is the difference between the Monthly 1-Year CMT index and the Monthly Treasury Average index?

The Monthly Treasury Average (MTA), also known as 12-Month Moving Average Treasury index (MAT) is calculated by averaging the previous 12 monthly values of the Monthly 1-Year CMT.

What is the difference between the 1-Year CMT and the 1-Year Treasury Bill index?

The index commonly called the 1-Year Treasury Bill is not a Treasury Bill index. It's the 1-Year CMT index. 1-Year Treasury Bills are no longer issued by the Treasury.

I want to compute the Weekly 10-Year CMT mortgage ARM index. Where can I find daily Constant Maturity Treasury rates to calculate each weekly average?

Weekly average values for each CMT have already been calculated and are contained in the H.15 Federal Reserve Statistical Release.

What happens to 1-Year CMT-indexed mortgage rates when the 1-Year CMT index rises?

The following graph reflects the movement of the 1-Year CMT-indexed mortgage rate and compares it with the monthly 1-Year CMT index.

I want to construct my own index: 3-Year Moving Average based on the 5-Year CMT that changes Monthly. How do I go about doing that?

Just add the 36 most recent monthly values for the 5-Year CMT together and divide the result by 36.

If you need historical data prior to 1990, please visit the Federal Reserve Board web site.

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