Statistics and public reports indicate that stock investment has developed to a popular and growing investment trend among individuals, where the underlying motivational factor is the possibility to generate a return on the investment, and therefore make money. A recurrent and controversial question in the financial context is how the individual investor should proceed to generate a return higher than the market. Although scientific research claims the market to be efficient, situations occur where individual performers manage to surpass the market, which is explained by deviations from the market’s efficiency. The deviations are known as market anomalies, and from the beginning of time several key ratio-anomalies have existed and disappeared. Despite their disappearance, some of these key ratios continue demonstrating the ability of forecasting returns. Therefore, the purpose of this essay is to use these key ratios to investigate the semi-strong form of market efficiency on the Swedish stock market during the period of 2013-2019. The execution will be done using key ratio-constructed stock portfolios based on the P/E-ratio, the B/M-ratio, and a combination of these. The portfolios will be compared both among themselves and towards a benchmark index with the intention to analyze if a significant return can be determined. According to the results, portfolios based on the P/E-ratio as well as the combination of the P/E-ratio and the B/M-ratio, can be used in portfolio construction to generate significantly risk-adjusted return on the Swedish stock market. This implicate that, during this investigation period, the Swedish stock market is not completely efficient according to the semi-strong form of market efficiency.