The main aim of this thesis is to analyze the behavior of stock price on ex-dividend day in London Stock Exchange and New York Stock Exchange and draw a conclusion about the market efficiency based. We collect 200 sample companies dividend, ex-dividend day and cum dividend day stock price to compare with NYSE composite index and FTSE 100 for London Stock Exchange.   To answer the research question and specific purpose of our thesis we developed five null hypothesis based on raw price ratio (RPR), market-adjusted price ratio (MAPR), raw price drop ratio (RPD), market-adjusted price drop ratio (MAPD) and market-adjusted abnormal return (MAAR). We used t-statistic to find the mean differences between observed values and standard values. We also show multiple regression analysis to show the relationship between ex-dividend day stock price and dividend, cum-dividend day stock price.   This thesis documented that same amount of stock price drop in 2008 New York Stock Exchange compare with dividend amount. In this case our null hypothesis accepted. On the other hand in London Stock Exchange shows higher drop of stock price than dividend amount in 2008 against the taxation rate rules of prior study. In 2007 both stock market shows the less drop of stock price than dividend amount. Therefore our null hypothesis rejected. We also documented that London Stock Exchange more volatile than New York Stock Exchange to consider the MAAR, tax rate and standard deviation. So we find significant evidence of market abnormal return which create an opportunity of market inefficiency and arbitrage opportunity for investors.   So, our thesis output shows mixed evidence for London Stock Exchange and New York Stock Exchange.

This is a study of the ex-dividend day. The study covers six years (2007-2012) and studies the shares included in the OMXS30 on the Stockholm stock exchange. OMXS30 is a share index of the 30 most actively traded stocks on the exchange. The study comprised a total of 145 observations. The purpose of this study is to investigate if the stock price on the ex-dividend day unfolds as the efficient market hypothesis teach or if there exists room for speculation, and thus earn a return higher than the market.The ex-dividend day effect has been studied previously, both on the Swedish market but also abroad. The results of previous researchers are different but they all have one thing in common, namely that there is a certain ex-dividend day effect.When calculating the ex-dividend day effect, the stock prices had to be adjusted for the normal return that occurs during the ex-dividend day. The normal return is not something that is universally known, but must be estimated by the author. In this study, it was estimated using the OMXS30 index movements relative to each company's beta. After that price drop ratio is calculated. The authors found that the share price on average fell by about 90 % of the dividend amount, with the possibility of an excess return of approximately 0.37 %. This was according to statistical tests significantly different from one, indicating that the ex-dividend day effect exists. By studying each year the authors found significant discrepancies between the years that cannot be explained, the authors themselves could conclude that the price drop ratio exists in symbiosis with the current economic situation.

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.