The Law of One Price : Evidence from Three European Stock Exchanges

Abstract: For the last decades the Efficient Market Hypothesis (EMH) has had a vital role in the financial theory. According to the theory assets, independent of geographic location, always are correctly priced due to the notion of information efficiency across financial markets. A consequence of EMH is the Law of One Price, hereafter simply the Law, which is the main concept of this thesis. The Law extends the analysis by stating that in a perfectly integrated and competitive market crosstraded assets should trade for the same common-currency price in every country. This becomes a fact due to the presence of arbitrageurs’ continuous vigilance in the financial markets, where any case of mispricing is acted upon in a matter of seconds by buying the cheaper asset and selling it where the price is higher in order to make a profit from the price gap. Past research reveals that mispricing on cross-traded assets does exist, indicating that there exists evidence of violations of the Law on financial markets. However, in the real world most likely only a few cases of mispricing equal arbitrage opportunities due to the fact that worldwide financial markets are not characterized by the perfect conditions required by Law. Consequently, it is of relevance to include factors that may have an impact on mispricing when implementing a validation test of the Law on cross-traded assets, as these may as well eliminate the assumed arbitrage opportunities. In this study the author implements a validation test of the Law by examining the degree of mispricing on 19 cross-traded assets in three European stock exchanges. Consequently, from the prevalent theoretical point of view, the author maps and analyzes the possible impact of market imperfections on the detected mispricings. The major finding of this study is that mispricing does exist to significant degree on the considered markets. However, by examining the possible impact of market imperfections, the author cannot disregard the fact that these may explain a considerable part of the detected price discrepancies. The final conclusion of this study is that the main focus when discussing mispricing should revolve round analyzing its underlying causes, rather than resting on tenacious financial theories, in order to be able to draw more comprehensive and fair conclusions about mispricing on cross-traded assets.