Mortgage innovation and house price booms

Abstract

We study how mortgage innovation can cause a housing boom even within a robust regulatory framework and strictly enforced recourse borrowing. Specifically, we find that the 2003 introduction of interest-only (IO) mortgages in Denmark ignited a housing boom that increased house prices 36 percent. In line with IO loans lowering debt-service payments and relaxing payment-to-income constraints, results show higher IO loan uptake and house price growth in areas with greater ex-ante benefits of such mortgages. Overall, our results are relevant for the many countries where IO loans play a sizable role in mortgage finance.