Semi Strong form of Efficient Market Hypothesis says that security prices fully reflect all publicly available information in a rapid and unbiased manner so that it is almost impossible for an investor to earn abnormal return by trading on that information. The main objective of the study to analyze the semi strong form efficiency of S & P CNX Nifty with respect to dividend announcement which is an event study methodology. Specifically, the study analyzes the effects of dividend announcement on stock prices on rate of return. The study has been done on secondary data which was published during the previous financial year (2015- 2016). The analysis concludes that the S & P CNX Nifty is efficient with respect to publically available information means dividend announcement does not possess the signaling property