The Cost of Funds Index inched minimally lower, though that was enough to establish a new all-time low.
As of September, COFI was 0.663 percent. It was the lowest level ever for the index based on data back to July 1981.
COFI slipped from August, when it was 0.667 percent — a record low at the time.
In the same month last year, COFIÂ was 0.957 percent.
The index, which is reported by the Federal Home Loan Bank of San Francisco, is determined based on interest expense at 11th District FHLBÂ members headquartered in Arizona, California and Nevada.
The most-recent index was calculated based on $15.3 billion in average total funds.
A small share of adjustable-rate mortgages are tied to COFI.
A far more widely used ARM index is the yield on the one-year Treasury note, which climbed to 0.13 percent as of the end of September from 0.09 percent at the end of the previous month.
However, the one-year Treasury yield has since retreated — finishing October at 0.11 percent.
ARMs accounted for 10.8 percent of all activity in the U.S. Mortgage Market Index report from LoanSifter/Optimal Blue and Mortgage Daily for the week ended Oct. 31.
