Testowanie występowania „efektu stycznia” na podstawie indeksu sWiG80

The aim of the study is to verify the impact of the “January effect” on the instruments on the Stock Exchange in Warsaw. To carry out the study calculated the average monthly returns of companies included in index sWIG80 for the period from January 2007 to December 2015. The calculations were based on daily quotations of selected indices, using a simple rate of return. A study shows that since 2007, the “January effect” has occurred in the stock market, once in 2012. Conclusions from the analysis of the results can be practically applied in making investment decisions.