Investors are continuously looking to increase the return on their investments. In an ideal world investors want to increase there return and outperform the market. Theory states that it is impossible to do so without increasing your risk. Arbitrage is a concept where investors are able to generate risk-free returns exceeding the market. Dividend is a common tool for publicly listed firms when rewarding their shareholders. On ex- dividend day, the day after the dividend payout, the stock price should according to theory decrease in order for the valuation of the stock to be held constant. In our research we investigate if there are arbitrage opportunities in connection to the dividend payouts, namely the ex-dividend effect. We want to generalize our results across experimental settings, thus across different stock markets. As a basis for our research we picked the OMXS. We base our research on three theoretical areas: the dividend irrelevancy theory, the efficient market hypothesis and the anchoring theory. The dividend irrelevancy relates to how the stock price ought to behave on ex-dividend day whereas the efficient market hypotheses states that prices on a market fully reflects all available information. Both theories concur that no arbitrage opportunities should be available on the financial market. The anchoring theory highlights the fact that investors formulate an anchor price for financial assets, for example stocks. In our research we aim to formulate a practical method on how to make abnormal returns on the ex dividend effect, based on the anchoring theory. Our census sample consists of dividend-paying firms publicly registered on the OMXS, and consists of 694 observations taken from 2009 to 2012. The sample was picked on the basis of characteristics, for example that the firm has been registered for at least four years and paid dividend one time during the four years of investigation. In order to tests for arbitrage opportunities on ex-dividend day, we used a simple mathematical model measuring the deviation between the price drop cum-dividend day to ex-dividend day, and the dividend amount. We conclude that the price drop differs from the dividend amount, only accounting for a price drop of 0.73 of the dividend amount. Thus, the price drop for each dividend unit is 0.73, in relation to a perfectly efficient market where there should be no difference; hence the price drop would be equal to the dividend amount, 1. Research on the ex-dividend effect is a thoroughly investigated area, where the first research was presented in 1955. Previous research all attempts to explain why there are market anomalies, but none examine how one can capitalize on the findings. In our research we examine if it is possible to make abnormal returns based on a segmenting of stocks, depending on their price volatility. This research is thereby first in examining how to capitalize on found arbitrage opportunities.