Abstract (eng)
In recent years, passive investing has gained popularity, and increasing shares of the stock market are held by passive investors, who tend not to react to new information as fast, if at all, as active investors. The efficient pricing of securities depends on market participants to accurately assess news and adapt their trading behaviour adequately. This thesis aims to examine whether increased passive investing leads to higher price inefficiency by means of a post-earnings-announcementdrift analysis. The results suggest a significant correlation between passive ownership and price inefficiency, confirming the research hypothesis. Surprisingly, the phenomenon of PEAD and market reaction behaviour seems to have changed in the latest years.