The West Coast-based index for adjustable-rate mortgages continued past the five-year-high mark.

In August, the 11th District Cost of Funds Index was 4.277% -- up 0.10% from July and about 1.41% higher than a year earlier, according to data released from the Federal Home Loan Bank of San Francisco on Friday.

The 27th consecutive monthly increase in the COFI during August pushed it up to the highest level since June 2001, FHLB data indicated.

Average total funds of $628.4 billion were reportedly used in the latest calculation of the COFI, which is computed from the actual interest expense reported for a given month by the Arizona, California, and Nevada savings institutions members of the bank.

The COFI, reported about 30 days following the end of each month, competes as the index for ARM applications, which the Mortgage Bankers Association reported last week represented about one quarter of total mortgage applications. Among the competing indexes are the 1-year Treasury-bill, which Thursday yielded 4.90 percent, according to Federal Reserve data, and the 6-month LIBOR, which Fannie Mae reported at 5.3704% for September.