This paper provides a theoretical analysis of the efficiency of prepayment penalties in a dynamic competitive lending model with risky borrowers and costly default. When considering improvements in the borrower's creditworthiness as one of the reasons for refinancing mortgages, we show that refinancing penalties can be welfare improving and that they can be particularly beneficial to riskier borrowers in the form of lower mortgage rates, reduced defaults, and increased availability of credit. Thus, a high concentration of prepayment penalties among the riskiest borrowers can be an outcome of efficient equilibrium in a mortgage market. We also provide empirical evidence that is consistent with the key predictions of our model.

We consider the optimal design of mortgage-backed securities (MBS) in a dynamic setting in which a mortgage underwriter with limited liability can engage in costly hidden effort to screen borrowers and can sell loans to investors. We show that (i) the timing of payments to the underwriter is the key incentive mechanism, (ii) the maturity of the optimal contract can be short, and that (iii) bundling mortgages is efficient as it allows investors to learn about underwriter effort more quickly, an information enhancement effect. Finally, we demonstrate that the optimal contract can be closely approximated by the “first loss piece.”