In what has become a routine event, the Monthly Treasury Average has descended to a new record low.
The MTA was 0.12083 percent during May, according to an analysis of data published by the Federal Reserve Board.
The index, which is used to determine rate and payment changes on some adjustable-rate mortgages, has never been this low based on data as far back as 1953.
In April, the MTA was a record-low 0.12250 percent.
During the same month last year, the index was 0.16333 percent.
The MTA is calculated based on the daily average of the one-year Treasury yield for the most recent 12 months.
The daily average for the one-year Treasury yield, itself, was 0.10 percent in May, while the one-year Treasury yield closed at 0.10 percent on Monday, according to Treasury Department data.
ARMs accounted for 12.2 percent of all pricing inquiries in the U.S. Mortgage Market Index report from LoanSifter-Optimal Blue and Mortgage Daily for the week ended May 30.