The Effects of After-Hours Information on Stock Prices and Trading Volume

Abstract

This study examines how after-market information over the weekend affects stock prices and trading volume for the next Monday in the Taiwan market. Because of the nature of causality and simultaneity that exists when the time period of data between independent and dependent variables overlaps, the control-time-lag method is proposed to address this issue. In contrast to the literature, the empirical results reveal investors’ information searching (attention) increases stock trading volume but is not effective for prices, indicating there may be noise traders in the market. To predict the price, it should return to the essence of the information, which is good or bad for the market. Moreover, this study finds that information-related factors are more important than companies’ fundamentals in affecting the Taiwan stock market.