FHFA Adjustable Rate Mortgage (ARM) Index is the average contract rate reported by a sample of mortgage lenders for fully amortized mortgage loans extended for the purchase of single family residences that were closed during the last 5 working days of the month. Before November 1991, the index was calculated based on the contract rates for loans closed during the first 5 working days of the month. Since November 1991, the index is calculated based on the contract rates for loans closed during the last 5 working days of the month.
The index is published monthly by Federal Housing Finance Agency (FHFA) and is derived from the data collected by FHFA from Monthly Interest Rate Survey (MIRS). The index is formally known as the National Average Contract Mortgage Rate for the Purchase of Previously Occupied Homes by Combined Lenders. FHFA also refers to it as Adjustable Rate Mortgage (ARM) Index.
The index is published monthly on the ARM Index webpage of FHFA website. The FHFA also makes the FHFA ARM Index information available on a recorded message on (202) 649-3993.
FHFA Adjustable Rate Mortgage (ARM) Index is used as an index to adjust interest rate on certain adjustable rate mortgages. This index was the only index rate that federally chartered savings and loan associations could use as an ARM index in the early 1980s. Till Sept 1989, this index was made available by the former Federal Home Loan Bank Board (FHLBB), and later by the Office of Thrift Supervision.
Updated: May 29, 2019