Freddie Mac Primary Mortgage Market Survey. Each week, since April 1971, Freddie Mac surveys lenders on the rates and points for their most popular 30-year fixed-rate, 15-year fixed-rate and 5/1 hybrid amortizing adjustable-rate mortgage products. The survey is based on first-lien prime conventional conforming home purchase mortgages with a loan-to-value of 80 percent. In addition, the adjustable-rate mortgage (ARM) products are indexed to U.S. Treasury yields and lenders are asked for both the initial coupon rate and points as well as the margin on the ARM products.