This paper deals with the forces behind stock market return in the U.S. In order to test the relationship, 10 variables are chosen and then applied to the APT model. The data is divided into three periods and then a linear regression is performed on each period. Throughout the three periods and thus through the period 1980-2011, Current Account, Money Supply and Price of Petroleum were not significant at any of the three periods at any level of significance. While the Consumer Confidence Indicator, Consumer Price Index, Federal Funds Rate, Treasury Security, Industrial Production, New Orders Index and Unemployment were significant on at least one occasion.