The Terminations Premium in Mortgage Coupon Rates: Evidence on the Integration of Mortgage and Bond Markets

During the Last three years mortgage rates have risen relative to yields on comparable maturity bonds. The questions addressed in the present paper are what is the extent of this increase and to what is it attributable? We find the increase between early 198 and early 1981 in coupon rates on GNMA mortgage pools relative to ''the" rate on a comparable portfolio of Treasury bonds to be about 100 basis points. We attribute the increase to a rise in the terminations premia built into mortgage coupon rates. The premia is the price borrowers are charged for the option to repay the mortgage when it is to their benefit (to refinance if interest rates decline). This price has risen in response to an increase in interest rate uncertainty. Our empirical results suggest that the increase is due to both greater uncertainty regarding the inflation premium in interest rates and the lesser weight the monetary authorities give to interest rate stability in their deliberations.