Following two consecutive monthly declines, the Cost of Funds Index edged higher. But another popular index for variable rate loans has tumbled over the past month.

COFI was 4.359% in August, the Federal Home Loan Bank of San Francisco reported Friday. The index rose from 4.277 % during July and August 2006.

The latest index was based on the cost of $452.8 billion in average total funds for 11th District members which are headquartered in Arizona, California and Nevada, according to FHLB data. Average funds were $437.8 billion the prior month.

COFI serves as an index for adjustable-rate mortgages, which accounted for 12.2 percent of applications tracked by the Mortgage Bankers Association during the week ending Sept. 21.

Another popular ARM index, the 1-year Treasury, yielded 4.03% Thursday, according to Federal Reserve data. A month earlier, the 1-year yield was 4.55%.

The 6-month London Interbank Offered Rate, another index used for U.S. ARM loans, was 5.14% for the week ended Sept. 26, falling from 5.43% a month earlier, Bankrate.com reported.