Asymmetric Information and Firms Trading Volume before a Scheduled Announcement: The Swiss Evidence

Abstract

It is generally known that trading volume is positively related to asymmetric information amongst investors, but when there is time discretion, the relation is likely to become negative. The aim of this paper is to empirically verify the existence of this inverse relation for a sample of Swiss listed firms. Trading volume trends are analysed before earnings announcements for a sample of 1540 events distributed across 85 firms from 1995 to 2006. I hypothesize that before an earnings announcement there is a decrease in the firm's trading liquidity due to the presence of asymmetric information amongst investors, and a positive relationship between trading volume and simultaneous changes in stock prices. Moreover, the magnitude of the price change should be higher in the case of a positive earnings release. Event analysis confirms a significant daily average decrease of about 2% in the abnormal volume turnover from 10 to 3 trading days before the announcement, while regression analysis reveals evidence that matching a lower decrease in trading liquidity there will be an upturn in the level of stock prices. Furthermore, the analysis reveals that prior to a positive announcement there will be a higher increase in the firm's share price. The analysis does not show evidence of any relationship between the decrease in trading liquidity, firm size and bid-ask spread.