In literature, impacts of macroeconomic factors on stock market and bond possess huge amount of studies. However, interaction between stock market yield and bond yield does not have prevalent studies. Therefore, the main purpose of this study is to analyze the interactions between S&P500 and 10-years tresury bonds in U.S. The study contains the period between 1985 and 2011. According to the empirical results of this study, while bond returns do not Granger cause to S&P500 returns, S&P500 returns do Granger cause to bond returns. That is, past returns of S&P500 to forecast the next day returns of bond return. Before applying Granger Causality test, the staionary of the variables is being tested via Augmented Dickey-Fuller (ADF), unit root tests are being examined and regression equation is being used.