The investment in stock market and other stocks issued by the firms require sufficient knowledge and understanding of the financial reports and information of the business firms. This study aims to investigate the effects of three types of financial ratios, i.e., profitability/liquidity, continuity and efficiency of business firms over the investors’ abnormal stock returns. To achieve the aim of the study, the ratios were categorized into two groups namely fundamental ratios and risk-proxy ratios. The financial ratios make a relationship between various economic variables of a firm and make it possible to compare financial information of various firms. The financial ratios also make it easier to evaluate the firm’s performance through examining the relationship between the variables of the financial statements. The results of this study showed that there is a significant relationship between the most fundamental accounting variables, i.e., return on assets, operational cash flow, changes in return on assets, changes in net profit margin and total asset turnover. The existence of this relationship shows the high dependence of abnormal stock returns on its intrinsic fundamental variables. However, there was not any relationship the liquidity ratio and stock returns. Moreover, there was not any significant relationship between the majority of risk proxy variables i.e., the ratio of accruals, operating leverage and stock issuance indicating the independence of abnormal stock returns from risk proxy variables.
The main hypothesis of this study was accepted with 99% confidence that the firms with higher F-Score have higher stock returns in comparison with the firms with lower F-Score. That is, we can claim with high confidence that the firms with more positive variables have a higher stock returns in comparison with the firms with more negative variables. Therefore, in their investments, the shareholders can consider this important factor and be sure about the increase of their assets and the return of their assets. Moreover, the univariate regression test showed that there is a significant relationship between most of the fundamental variables including return on assets, cash flow from operations, changes in return on assets, changes in net profit margin and change in total assets turnover indicating the strong significant relationship between abnormal stock returns and their intrinsic fundamental variables. However, there was not found any relationship between cash flow ratio (liquidity) and stock returns. Moreover, there was not a significant relationship between most of the risk proxy variables including the ratio of accruals, operating leverage and stock issuance representing that abnormal stock returns are independent from risk proxy variables. On the other hand, the findings of testing the sub-hypotheses based on multivariate regression analysis showed that only three sub-hypotheses were confirmed. It means that there is a significant relationship between three variables of return on equity ratio, changes in return on equity ratio and ratio of accruals with the abnormal stock returns. The results of the study showed that these three variables alone can explain about 18% of the variations in stock returns. The results of this study indicate the significance of investigating the financial variables in general and the fundamental accounting variables in particular to explain the stock returns of the firms. So, the findings of this study signify that investors, firms and all other parties in capital market need to pay sufficient attention to such variables. The results of the study showed that the firms with higher F-Score have higher stock returns in comparison with the firms with lower F-Score. Therefore, in their investments, the shareholders are suggested to consider the results of this study in general and the variables under study in particular. Moreover, due to the significance of financial information, the Standard Organization in Iran and Tehran Stock Exchange are suggested to determine some measure to validate and increase the quality of accounting information