This study addresses the general reaction a firm's stock price has when the firm receives a patent and looks at the implications such reactions have on the Efficient Market Hypothesis. The study introduces the underlying theory and relevant literature to develop the foundation needed to assess these connections. The literature that examines the EMH is unmistakably extensive. Nonetheless, literature that looks at it in relation to patent grants is quite limited. This study uses an event study to examine a sample of 90 patents from 5443 patents that were granted during a five year period (1999-2004) to chemical companies. Through the use of four statistical models which attempt to control for what the price of each security would be if a patent was not granted, the results of this study are able to assess the general reaction of the stock market to the granting of patents to chemical companies. The primary conclusion of this study is that the stock prices of chemical companies do not react to the granting of a randomly selected patent. Specifically, there were no statistically significant abnormal or cumulative abnormal returns found near the time of patent grants. This finding thus enriches the current literature relating to market value and innovation.