Mortgage rates fell this week as investors grew anxious about corporate earnings. As stock prices fell, bond yields declined, too — and so did mortgage rates.

The benchmark 30-year fixed-rate mortgage fell 5 basis points, to 6.48 percent, according to the Bankrate.com national survey of large lenders. A basis point is one-hundredth of 1 percentage point. The mortgages in this week’s survey had an average total of 0.37 discount and origination points. One year ago, the mortgage index was 6.78 percent; four weeks ago, it was 6.52 percent.

The benchmark 15-year fixed-rate mortgage fell 8 basis points, to 6.01 percent. The benchmark 5/1 adjustable-rate mortgage fell 4 basis points, to 6.05 percent. The 30-year jumbo, for bigger mortgages, fell 5 basis points, to 7.64 percent.