Prepayment behaviors of Japanese residential mortgages

We investigate full prepayments of Japanese residential mortgages during a ten-year period from 1996 to 2005. This investigation is important because the amount of mortgages outstanding in Japan is huge, yet the study on their prepayments is very limited. This period from 1996 to 2005 was characterized by two distinct features of the evolution of interest rates that might have significant effects on mortgage refinancing. First, interest rate fluctuations were limited to a narrow range of a little over 1%. Surprisingly, full prepayments of Japanese mortgages were sensitive to small changes in interest rates. Second, long-term refinance rates did not fall well below the contract rates of most mortgages in our sample during the ten-year period, while short-term refinance rates did. With this interest rate relationship, if mortgagors ever refinanced, it was likely that they rolled over short-term mortgage rates several times until they repaid mortgages completely. Hence, we examine the sensitivity of full prepayments to short-term vs. long-term interest rates, mortgagors' expectation of future course of interest rates (by the slope of yield curve), and that of interest rate volatility. Our analysis shows that short-term interest rates have a slightly greater explanatory power for full prepayments than long-term interest rates. In addition, our analysis confirms that full prepayments are sensitive to both the slope of yield curve and interest rate volatility. Other issues we look into are the patterns of full prepayments in relation to loan age and seasonality. We find that the pattern of full prepayments relative to loan age is comparable to that of mortgages in the U.S., and that the seasonal pattern of full prepayments is attributable to relevant institutional arrangements in Japan.