Abstract:Selecting analysts earnings forecasts from 2010 to 2015, heavily held stocks and data on commission paid to securities traders by fund firms, this paper makes a research on the consequences of analysts optimistic earnings forecast for heavily held stocks by fund firms. The research shows that the more times the analysts issue optimistic earnings forecast for stocks held by fund firms, the more commission the fund will pay to the firms analysts. Further research finds that the earlier optimistic forecasts for unpopular stocks heavily held by fund firms and more timely optimistic forecasts made by analysts could increase commissions and sub positions paid by fund firms to securities traders. This phenomenon is more obvious in small sized fund firms. Finally, the fund firms pay more commissions to securities traders by means of increasing the volume of transactions; Interest conflict is the cause of dissimilation of analysts behavior.