Overnight public information, order placement, and price discovery during the pre-opening period

This study examines the impact of corporate news announcements released overnight on price discovery during the pre-opening period in the Australian Securities Exchange. Our results suggest that the presence of these announcements increases the efficiency of indicative opening prices and that the intensity of these announcements significantly influences the aggressiveness of pre-opening orders. Using earnings announcements to compare the speed of price adjustments in response to overnight and daytime information of a homogeneous type, we find that prices respond immediately to overnight news upon the commencement of trading, whereas adjustments based on trading-hours news tend not to be instantaneous. Overall, our evidence highlights the important role of the pre-opening period in price discovery and the prospect of further enhancing this role by timing the release of public information to occur during non-trading hours.

► Corporate overnight news increases the efficiency of indicative opening prices. ► Corporate overnight news influences the aggressiveness of pre-opening orders. ► Stock prices incorporate overnight earnings news immediately upon trading. ► Stock price adjustments to daytime earnings news are not instantaneous. ► We highlight an important role of the pre-opening period in price discovery.