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.

Forskningen kring effektiva marknader är uppdelad; ena sidan påstår att marknaden är fullständigt effektiv och det inte går att skapa någon form av överavkastning. Andra sidan hävdar tvärtemot att endast historisk information reflekteras i dagens priser. På kort sikt kan det finns en viss ineffektivitet och de flesta erkänner att marknaden innehåller anomalier Syftet med denna studie är att undersöka om det existerar systematiska fel beträffande informationsflöden som pekar mot att den svenska aktiemarknaden inte är av semi-stark form eller stark form av effektivitet Vi utgår från tre metodologiska ställningstaganden; utgångspunkt, forskningsansats samt kunskapssyn. En deduktivt kvantitativ metod tillämpas och vi applicerar metoden för event study. Vi finner stöd för att det finns systematiska fel i marknaden beträffande informationsflöden i form av aktierekommendationer. Resultaten antyder att den svenska aktiemarknaden inte är av starkt effektiv form och i ett fall av fyra finner vi att den inte heller besitter semi-stark form. / Research concerning efficient markets are divided into two camps; the one hand, claims that the market is fully efficient and it is not possible to create any kind of excess returns. The other side argues the contrary that only historical information are reflected in today’s prices. Short term, there is some inefficiency and most recognize that the market contain anomalies The purpose is to investigate whether there exist indications regarding flows of information to the Swedish stock market suggesting a semi-strong form or strong form of efficiency. We start from three methodological statements; starting point, the research approach and epistemological beliefs. A deductive quantitative methodology is used, and we apply the method of event study. We find evidence for the existence of systematic errors in the market in terms of flows of information in the form of stock recommendations. The results suggest that the Swedish stock market is not of the strong efficient form and in one case out of four, we find that it does not possess the semi-strong form.