Comments and Discussion

摘要

In this paper, Tomasz Piskorski and Amit Seru bring new data and recent experiences from the Great Recession to bear on an old question in mortgage finance: What is the optimal way to design a mortgage contract? The answer to this question has far-reaching implications for both macroeconomic stability and individual household welfare. Residential mortgages were at the heart of the 2008-09 financial crisis, and several features of their design directly impeded policy efforts aimed at providing debt relief and economic stimulus to households during the recession.As in much prior work on this topic, Piskorski and Seru's primary focus is on the nature and extent of risk-sharing between borrowers and lenders in the mortgage market. Broadly speaking, their paper can be read as both a clarion call for greater state contingency in mortgage contract design and a set of practical suggestions for how to best achieve this goal. To build their argument, Piskorski and Seru proceed in three steps. First, they provide a review of the theoretical literature on mortgage market design and a taxonomy of the various mortgage contract rigidities that held back policy efforts to relieve household debt during the Great Recession. Second, they present a simple model that incorporates insights from this literature to highlight the potential welfare gains from state-contingent mortgage contracts that index borrower payments to economic conditions such as house prices or income. Finally, they document a set of new empirical facts about the spatial and time-series variation in local economic conditions, which together underscore the potential benefits of indexing mortgage payments to local rather than national conditions.