Stockholm stock exchange efficiency : Abnormal returns on positive annual and interim reports

Abstract: Problem: An efficient market fully reflects all available information about a company in its share price. Furthermore any new information presented about a company will lead to an instant adaptation in the share price. Henceforth an investor can not reach abnormal returns on an efficient market. The Stockholm stock exchange is afairly large stock exchange with a turnover of SEK 14000 millions per day. Prior studies conducted regarding the efficiency of the Stockholm stock exchange have stated that the stock exchange was efficient on a semistrong level. However these studies were conducted with a time frame of several weeks and therefore the authors distinguished a need for a study aiming at short term efficiency. Furthermore this thesis aims to investigate the effects of the presentation of positive annual and interim reports. A positive report is defined as a report that leads to an increase in share price the day it is presented and consequently includes all events on the day of the presentation, e.g. the press conference. The thesis was written from an investors’ perspective, who is about to buy shares. Purpose: The purpose of this thesis was to describe and analyze the Stockholm stock exchange market’s efficiency. This was done during the days surrounding the presentation of annual and interim reports rendering an increase in share price. Furthermore the possibilities of making abnormal returns by buying shares during this period were investigated. Method: To investigate the efficiency of the Stockholm stock exchange an event study was carried out. Data regarding the performance of the shares of the fifteen most traded com-panies on the Stockholm stock exchange were collected from the OMX groups’ homepage. The chosen companies together represented more than fifty percent of the turnover of the OMXS 30 index. The index was used as a benchmark for measuring the efficiency. The share price movement was analyzed with a quantitative approach through a statistical T-test with the assistance of the SPSS 13.0. Result: The authors claim that the Stockholm stock exchange is not efficient on a semistrong level the day after the presentation of a positive report, as the shares displayed a negative abnormal deviation from the OMXS 30 index. The deviation was statistically verified. However the authors state that no abnormal returns can be reached by buying shares during this period since the deviation was negative. The period as a whole and the other tested days came out as efficient on a semi-strong level.