The credit union edged out Puerto Rico-based Scotiabank de Puerto Rico by 13 basis points.
Meanwhile, overall rates continue to decline. SNL reported in its survey the average nationwide rate for a 30-year fixed mortgage was 3.51% on Dec. 19, with the average 15-year rate coming in at 2.93%.
Both averages are significantly below the 3.85% 30-year rate and the 3.20% 15-year rate posted in the previous, late-June analysis.
The lowest rates in the country can be found in Alaska, reported SNL, with the 15-year mortgage average at 2.63% and the average 30-year rate at 3.29%.
Montana came in second place for both products, offering an average of 2.68% on a 15-year mortgage and 3.33% on a 30-year mortgage.