What Is the Monthly🦩 Treasury Average (༺MTA) Index?

The Monthly Treasury Average (MTA) is an interest rate index derived from the 12-month moving average (MA) of 澳洲幸运5官方开奖结果体彩网:one-year constant maturity Tr🙈easury bonds (one-year CMT). 

The MTA acts as the basis to set interest rates for some 澳洲幸运5官方开奖结果体彩网:adjustable-rate mortgages (ARMs). The MTA Index, also known as the 12-MAT, is a lagging indicator that changes after the econo🅺my has begun to follow a particular 🧸pattern or trend.  

Undersဣtanding the Monthly Treasury Average Index

The calculation for the index comes from adding the twelve most recent monthly CMT interest or yield values and dividing൩ by twelve. The one-year constant maturity Treasury (one-year CMT) is the implied, one-year yield of the most recently auctioned ❀U.S. Treasury bills, notes, and bonds.

When the twelve-monthly CMT values are sequentially increasing, the current MTA value will be lower than the current CMT value. Conversely, when the CMT values fall month after month, the MTA will appear higher than the current CMT. This inverse relationship has the effect of making the MTA Index smoother or less volatile than other interest indexes, such as the 澳洲幸运5官方开奖结果体彩网:one-month LIBOR or the CMT itself.

In times of extreme interest rate 澳洲幸运5官方开奖结果体彩网:volatility, the difference between the MTA, CMT, and other indexes can be sub✱stantial. For example, during the lꦦate 1970s and early 1980s, when interest rates were in the double digits and fluctuating widely, the MTA Index often differed from the CMT rate by as much as four percentage points. 

Note, however, that the difference could be either up or down, depending on the direction rates were flowing at the time of average calculation. In Dec. 2024, the MTA Index was pegged at 4.68%; the CMT was at 4.17%.

Choosing an Index for a Mortgage

Some mortgages, such as 澳洲幸运5官方开奖结果体彩网:payment option ARMs, offer the borrower a choice of indexes. The index should be chosen after analyzing the available options. While the MTA index is typically lower than the one-month LIBOR by about 0.1% to 0.5%, the lower rate of an MTA, combined with a payment cap, can cause a negative amortization situation. In negative amortization, the monthly payment is less than the interest owed on the loan. In that case, unpaid interest adds to the principal, which is subject to more interest in the following months. Also, in p𒆙eriods of falling interest rates, the MTA will cost more due to its lagging effect.

The interest rate on an adjustable-rate mortgage is known as the fully indexed interest rate. This rate 🤪;equals the index value plღus a margin. While the index is variable, the margin is a fixed value for the life of the mortgage. 

When considering which index is most economical, do not forget to add in the margin amount. The lower an index relative to another index, the higher the margin is likely to be. A mortgage pegged to the MTA Index typically includes a margin of 2.5%.

The Bottom Line

If you're shopping for an adjustable-rate mortgage, you may see the term MTA. The Monthly Treasury Average is a rates index that is used as a financial indicator that helps set the interest rates for an ARM. Since it's an average of 12 months' worth of data, it's considered to be a lagging indicator.