Studying the relationship between the sizes of firms accepted in Stock Exchange and their operating performances emphasizing at industry agent: Evidence from Iran

The size of a company shows different perspectives of it in several studies. The present research is going to study the effect of the sizes of firms accepted in Tehran Stock Exchange on their operating performances. Our statistical sample includes 66 firms during the time period between 2006 and 2010. The statistical method used in this research includes the independent t test and a bidirectional variance analysis method. The findings of the research show that the size of the firms affects criteria such as ROA, ROE, REVA, MVA, P/E, M/B, and Q statistically and it does not affect criteria such as EPS, ROI, RI, and EVA. Also regarding EPS and EVA, we can say that firms with big sizes affect these criteria the most and small firms have the least effects on ROI and RI criteria. Also in studying the simultaneous effects of the type of the industry and the sizes of firms on operating performances of them each of operating performance approaches (accounting, financial, value added and integrative approaches) is affected by the industry agent.