EXAMINING THE RELATIONSHIP BETWEEN COMPETITION STRUCTURE OF PRODUCT MARKET AND LEVEL OF DISCLOSURE IN IRANIAN COMPANIES (CASE STUDY: COMPANIES LISTED ON TEHRAN STOCK EXCHANGE)

Pricing power of product market is an important factor affecting earnings management. There have been used the adjusted Lerner index, Hirfendal-Hirschman index and measurement standard of optional abnormal accrual items according to Kaznic model (1999) to examine the effects of pricing power of product market, industry structure and earning management respectively. The research is correlation type that examines the relationship between independent and dependent variables. Its population consists of 114 companies listed in Tehran Stock Exchange, which they were studied from 2006 to 2013. For statistical analysis, there have been used quantitative methods including multivariate regression analysis based on panel data. To analyze, there have also been used E-Views, Excel and Stata software. The results show a significant effect pricing power of product market on earnings management, but industry structure has no a significant effect on excess returns.