Does Size Matter? : Abnormal Returns and Market Efficiency at Stockholm Stock Exchange

Background and purpose In Sweden private savings in stocks has experienced a large increase and in year 2006 there were 6.7 million people, or 77 per cent of the population owning stocks. A recent study shows that more than every other Swede has deficient knowledge in trading with stocks. Since small private investors often do not know how to gather and interpret information they must utilize investment advices. The large increase in private savings in stocks, the lack of investment knowledge together with the large increase in Internet usage has resulted in investment advice seeking on the Internet. One of the largest sources of investment advices on the Internet in Sweden today is Avanza.se. The purpose with our thesis is to describe and analyze if, after a buy recommendation issued at Avanza’s website, the effects with respect to abnormal return and market efficiency differ significantly depending on a company’s capitalization value. Method We have used a quantitative approach to fulfill our purpose. The secondary data required to do so was gathered from the OMX-Group’s website, where historical prices and Index information was collected, and from the online broker Avanza’s website where the buy recommendations were compiled. In order to conduct statistical tests and calculations we have used the statistical software SPSS. Frame of Reference The theories we made use of mainly treated market efficiency and abnormal return. Conclusions We have seen that the recommendations’ effect concerning abnormal return differ signifi-cantly depending on capitalization value, where the effect on companies with smaller capitalization values are larger. We have also found tendencies of market inefficiency at the semi strong level for stocks with smaller capitalization value