Förekommer insider trading på Stockholmsbörsen?

Sammanfattning: We have investigated whether insider trading occurs on Nasdaq OMX Stockholm, the Stockholm Stock Exchange. Insider trading refers to transactions made by persons, or those closest to them, within a company that has insight and access to information that is either confidential or has not yet been communicated to the market. There is disagreement on whether insider trading is harmful to the marketplace as a whole. Some theories claim that the companies' cost of capital increases when insider trading occurs while others say insiders increases the efficiency of market pricing. Despite the difficulty in finding clear evidence that insider trading affects other investors negatively, chances are that only the suspicion might be enough to scare away other investors from investing as long as insider trading occurs. This would reduce market liquidity and impair firms' ability to attract new capital from outside investors. This is one of the reasons that insiders of Swedish listed companies are prohibited, by Act (2005:377) on penalties for market abuse when trading financial instruments, to use the confidential information they possess when taking decisions on share transactions. We have performed our study by testing for the presence of abnormal returns for insiders in companies listed on each of the Stockholm Stock Exchange’s three lists: Large Cap, Mid Cap and Small Cap during 2013. The outcome we of our study shows that insiders manage to get abnormal returns over a six month period following a stock transaction. It is mainly through purchase transactions that insiders manage to get a higher return than would normally be expected based on the Dimson-March model we used to generate expected returns. We also found that there is a big difference between the abnormal returns made by insiders due to their inside company’s size measured by capitalization. Our results indicate that confidential information in small companies is most valuable because it is among the insiders of small cap companies that the largest abnormal returns occurred in our study.