A new hypothesis, The Adaptive Markets Hypothesis (AMH), is applied to the Swedish stockmarket context by testing the variability of the risk-return trade-off over different investment horizons and market environments. Yearly returns and volatility are measured on OMXS30 index between1986 and 2017 over a variety of different investment horizons. Through the sample observations, a number of distinct market environments become apparent. A regression analysis is then used to test the statistical significance of the risk-return relationship. The results show a weak – and varying – statistical relationship between risk and return, implying that risk is not a reliable explanatory variable for average returns. The length of the investment horizon and the market environment the investment is being made in are shown to be influential factors on changes to the risk-return relationship. These findings from the OMXS30 index support the AMH, showing that the risk-return relationship is dynamic and subject to changes over different investment horizons and in different market environments.

This study investigates, with a critical approach, if portfolios consisting of high beta stocks yields more than portfolios consisting of low beta stocks in the Swedish stock exchange market. The chosen period is 1999-2016, covering both the DotCom Bubble and the financial crisis of 2008. We also investigate if the Capital Asset Pricing Model is valid by doing a test similar to Fama and Macbeth’s of 1973. Based on earlier studies in the field and our own study we come to the conclusion that high beta stocks does not outperform low beta stocks in the Swedish stock market 1999-2016. We believe that this relationship arises from inefficiencies in the market and irrational investing. By doing this study we observe that, the use of beta as the only risk factor for explaining expected returns on stocks or portfolios is not correct.