How do US sectoral markets connect in calm and crisis? A quantile-based network analysis

Abstract

This work investigates how the return coherence of the US sectoral market changed during/post COVID-19 from the pre-pandemic period. We sampled daily data for a pre-COVID-19 period from January 2018 to November 2019 and a during/post-COVID-19 period from December 2019 to August 2024. To compare the return coherence and spillover for these periods, we applied quantile cross-spectral (Baruník & Kley, 2015) and network connectedness (Diebold & Yilmaz, 2014) measures, respectively. Our results highlighted a substantial increase in the integration level of US sectoral returns during/post-COVID-19 period. The effects of COVID-19 on returns were found to be more prominent with a short-run investment horizon under extreme market conditions. However, the coherence of energy sector returns with all other sectors remained low during/post-COVID-19 period under normal and bullish market conditions, thereby offering optimal opportunities for investment.