This article examines the effect that allowing institutional traders to invest in the futures market had on the Taiwan stock market. The study is based on daily trading records from 2 July 2007 to 31 December 2009-a total of 682 daily data sets. The research procedure involves identifying the stationality of a time series for each variable using the Augmented Dickey-Fuller unit root test, a serial correlation test with the Ljung-Box test, causality tests using Granger's methodology, and the estimation of a vector autoregressive (VAR) model. The results show that some of the variables under investigation are interrelated. In terms of estimating the VAR model, the impact that opening futures trade to institutional investors has had no significant effect on the Taiwan stock market.