The Extended Opening Session of Futures Market and Stock Price: Evidence from the Taiwan Stock Exchange

This paper examines how the introduction of the extended opening session of the futures market affects stock price behavior around the market opening. On January 1, 2001, the Taiwan Futures Exchange (TAIFEX) extended the trading hours by opening earlier 15 minutes than the Taiwan Stock Exchange (TWSE). This change presents an opportunity to analyze how the extended opening session of futures market affects stock price behavior. Compared with the pre-extension period, the empirical results show that stock returns are less volatile and return auto-correlations are less positively correlated around the stock market opening. Moreover, overreaction for opening prices of the stock market is mitigated in the post-extension period. Finally, unexpected futures returns during the extended opening session can predict overnight stock returns. Overall, the empirical results are consistent with Foster and Viswanathan (1990) in that informed traders will trade aggressively at the market opening.