Abstract
The adjustable-rate mortgages have gradually become the mainstream in the mortgage market in Taiwan. Comparing to the adjustable-rate mortgage products in foreign countries, such as the United States domestic ones seem to be simpler and less categories. This study elaborates the characters of option adjustable-rate mortgages (Option ARMs), and differentiates these from traditional adjustable-rate mortgages. Therefore, we can compare the value between these two products which use three kinds of prepayment models, and also using sensitivity analysis to develop more accurate evaluation. The price of Option ARMs is higher than traditional adjustable-rate mortgages by the result of simulations. By the way, the price of traditional adjustable-rate mortgages which use OTS prepayment model is also higher than those which use CPR or PSA prepayment model. Further more, the price of traditional adjustable-rate mortgages which use PSA prepayment model is almost the same as CPR in the normal prepaying speed. The volatility of interest rate and the limitation in negative amortization both go the negative way with Option ARMs, others are go the positive way. Key words: adjustable-rate mortgage, option ARM, pricing mortgage