|It's been more than half a century since the Monthly Treasury Average has been this low.
The index descended to 1.21000% last month, according to data reported by the Federal Reserve.
MTA -- which is the 12-month average of the monthly Treasury yield -- was 1.33917% during April and 3.29000% in May 2008.
May's MTA was the lowest since April 1955, when it stood at 1.18667%, according to an analysis of Federal Reserve data by MortgageDaily.com.
Another index used for adjustable-rate mortgages is the yield on the one-year Treasury bill, which ended May at 0.47% -- lower than 0.49% at the end of April -- data from the U.S. Department of the Treasury indicated. The one-year yield closed at 0.48% yesterday.
The six-month London Interbank Offered Rate ended last month at 1.22%, lower than 1.58% at the end of April, Bankrate.com reported.
The ARM share of loan applications in the Mortgage Bankers Association Weekly Mortgage Applications Survey for the week ending May 22 was 2.6%.