Borrowers whose adjustable-rate mortgages change with the Monthly Treasury Average were stung with a surge in the index.
An analysis of Federal Reserve Board data indicates that MTA worked out to 0.32167 percent for the month of December.
The last time the index was that high was in November 2010, when MTA stood at 0.32500 percent — a record-low at the time.
As of November 2015, the index was 0.28500 percent, while it landed at 0.12083 percent as of Dec. 31, 2014.
MTA is determined based on the daily average of the one-year Treasury yield for the most-recent 12 months.
The daily average was 0.65 percent in December.
But the one-year Treasury yield, itself, is a far more universally utilized index for ARM products.
As of the end of December 2015, the yield on the one-year Treasury was
0.65 percent, elevated from 0.51 percent at the end of November.
ARMs made up 21.3 percent of all business in the U.S. Mortgage Market Index report from OpenClose and Mortgage Daily for the week ended Jan. 1, 2016.
ARM share surged from 11.9 percent just a week earlier.
