Efficiency plays essential role for improving the performance of banking industry. In this paper, we present an empirical investigation to study the effect of efficiency on abnormal return. The proposed study collects the necessary information from official statements as well as historical data over the period 2009-2013 reported on Tehran Stock Exchange to examine the relationship between efficiency and abnormal return. Using regression analysis, the study has determined a meaningful, positive but weak relationship between abnormal return and efficiency. However, the study does not find any meaningful relationship between bank size and abnormal return.

The purpose of this paper is to study the effect of the tax expenses on accounting conservatism on firms listed on Tehran Stock Exchange. In this study to measure the conservatism accruals is used to test the research hypotheses based on the information gathered from 61 firms listed on Tehran Stock Exchange over the period 2004-2009. Findings indicate that the relationship between conservatism accounting and corporate tax burden was positive and significant. In addition, firms with high book-tax conformity had higher motivation to use the conservative accounting to reduce their tax payments.