Effect of Income Smoothing on Unsystematic Risks of Companies Listed in Tehran Stock Exchange

This study investigates the effect of income smoothing on unsystematic risk of the companies listed in the Tehran stock exchange. Eckel model is used to identify the smoother companies. In the first hypothesis, a simple linear regression test is used to specify the effect of income smoothing on unsystematic risk of the companies. Then, the relationship between factors affecting income smoothing behavior and unsystematic risk of the companies is investigated, using linear multiple regression test. In the second to sixth hypotheses, the variables of company size, liquidity ratio, liability contract, income variability and industry type are regarded as independent variables, and unsystematic risk as dependent variable. In this research, the number of sample data for a 10-yearperiod from 1381 to 1390 accounted to 650 year-company. The findings of the research indicated that income smoothing reduces unsystematic risk, and the factors representing company size, liquidity ratio, liability contract, income variability and industry type have significant relationships with unsystematic risk.