In this paper, we study how China's stock market reacts to the sudden outbreak of COVID-19 in 2020, particularly to the announcement of the pandemic lockdown. In general, we observe reversals both at the industry level and at the firm level due to investors' overreactions to the pandemic lockdown. For industry- and firm-level stocks with positive cumulative abnormal returns (CARs) in the event window when Wuhan was locked down, the reversals are stronger. Thus, the reversal effects are mostly dr