Mortgages play a significant role in the US economy. Americans predominantly use fixed-rate mortgages (FRMs) to avoid interest rate risk, but related risk aversion cost has not been analyzed yet. This paper fills gap by investigating of choosing FRMs over adjustable-rate (ARMs). We find that ex post, FRM borrowers made 12% – 23% higher payments 0.66% 1.62% potential ARM payment shocks. Conseque...