Financial incentive to prepay in fixed-rate mortgages

The borrower's financial incentive to prepay is a crucial determinant in estimating prepayment in mortgage pools and, consequently, in valuing mortgage-backed securities. In mortgage prepayment literature, this incentive to prepay has been proxied by both the ratio of the loan rate to the refinancing rate and by the arithmetic spread between the two rates; however, the former is considered to be a better proxy of the refinancing incentive than the latter by a section of the literature. In this paper, the authors check the accuracy of that statement and subsequently estimate two prepayment functions using, alternatively, the two proxies. The results indicate that the use of the ratio does no…