Asymmetric Post Earnings Announcement Drift and Order Flow Imbalance : The Impact on Stock Market Returns

We conduct an event study around the earning announcement to examine the asymmetric post earnings announcement drift, and its relationship with the bid-ask bias, order follow imbalance on post earnings announcement period for UK stock market from 2000-2021. The earning drift is significantly asymmetric in the post earnings announcement period, stocks with good news have less drift, and it (at least) partly due to the order flow imbalance during the event period. The earning announcement attracts more sell than buy orders, and an overall negative reaction in the market. The difference between transaction price return and quote price returns shows that the bid-ask bias is also a possible explanation of post earnings announcement drift