The Impact of Product Market Competition on Earnings Management of the Companies Listed in Tehran Stock Exchange

This paper investigates the relation between product market competition and earnings management of the companies listed in Tehran Stock Exchange (TSE). Therefore, the Herfindahl-Hirschman, Lerner, and Modified Lerner indexes were employed as a proxy for product market competition. Also, in our research use the discretionary accruals as a proxy for earnings management. The research population composes of 67 companies listed on Tehran Stock Exchange which have been studied during the years 2004 to 2011. Multivariate linear regression statistical analysis was used to test the hypotheses of the research. The results suggest that there is a significant negative relationship between product market competition (i.e., Herfindahl-Hirschman, Lerner, and Modified Lerner indexes) and earnings management.