House price bubbles under the COVID-19 pandemic

We analyze bubble formations in house prices under the COVID-19 pandemic in 382 metropolitan areas in the U.S. with a special attention to the role of population density. We use a robust sieve-bootstrap version of the right-tailed unit root test procedure to identify periods of explosiveness in price–rent ratios across metro areas when controlling for fundamentals such as mortgage debt financing costs and the wealth of households. The bubble tests reveal evidence of explosive house prices during the COVID-19 pandemic but with important cross-area differences. In contrast to earlier bubble episodes, we find that the frequency and size of bubble formations under the pandemic have been stronger in low-density metro areas compared to high-density metro areas.