Some researchers have classified institutional investors into two groups. According to them, the first group are investors that focus on short-term earnings and the second group include professional investors, who’s relative advantage is in gathering and analysis of more data regarding future earnings which is not refelected in reported income. Thus, as the number of this type of investors increases in the capital market, the share prices will reflect more information regarding future returns and therefore information asymmetry logically should decrease.
The purpose of this study is to provide evidence on the role of the second type of institutional investors in decreasing information asymmetry in Tehran Stock exchange. To conduct the empirical tests we obtained two distinct sample of invested companies. One with low and the other with high degree of institutional ownership. The result of our study showed that the latter companies reported more information related to future earnings than the former ones. Therefore, more information asymmetry is observed in the invested companies with low degree of first group of institutional investors. The intervening variables such as size, book to market value ratio and financial leverage were under control in our study.