Objective: The aim of this study is to investigate the relationship between the debt leverage and the audit fees in the Tehran Stock Exchange. We considered the impact of the operating and financial liability leverage variables. In addition, the existing association between the mentioned variables and the audit fees was examined. Methods: In this research, the statistical population is 113 firms during the periods of 2011 to 2018 years. We used the multivariate regression to examine the relationship between research variables. Results: Considering the results, the total debt leverage, the financial leverage, and the estimated operating liability leverage have positive and significant nexus with the audit fees. The high liability leverage increases the risk of client failure and the risk of auditor litigation; the auditors react to these risks and increase audit fees. Also there is no tie between changes in all debt leverages and changes in audit fees. The additional tests in study show that the higher level of total debt leverage and the financial leverage in small and large firms raise the audit fees. Since the financial leverage in situation of financial distress is high, the auditors with higher fees decrease the audit risk. Based on the results we can see there is also a positive and significant link between the total debt leverage, the financial leverage, and the estimated operating liability leverage with the abnormal audit fees. As well, the delay's relationship in presentation of the audit report as a measure of the auditor's effort with their interactive effect with leverage has no influence on the audit fees. Conclusion: This article investigated the Distinction between different types of leverages in audit studies. The results show this paper adds to the existing literature in the accounting and auditing context, particularly, agency theory field. As the higher debt leverage has relation with lower-quality earnings and the higher-risk audit, the conflict of interest occurs between the shareholders and the managers. The auditors have the important role in resolving this conflict of interest by examing the financial statements. According to the findings of this study, it can be suggested that recognizing the different sources of leverages and the distinction between financial and operating leverage is important in auditing research, especially audit fee models. Therefore, the clients and audit firms interested in estimating the audit fees accurately can utilize the appropriate model, that is, this study has provided a unique insight into the literature in the context of audit fees.

Companies provide their investment expenses and their own operation through financing from a different sources. Selection of the best method of financing is the responsibility of financial managers. This can be done through liabilities or distribution of stocks. In the present study, operational liabilities as a crucial means of financing were investigated in terms of their future return in 110 stockholder companies confirmed by Tehran Stock Exchange during 2008 to 2013. Methodology was a descriptive one based on regression analysis through compound data. Findings showed that there was significant relationship between operating liability leverage, Contractual Operating liability leverage and future return of companies’ stockholders. Further, overall lever leads to a balance between lever of operational liability and future return of shareholders. Besides filling the gap in this field, implications of the study would be efficient for managers and investors too.

The operating performance of a firm is not directly observable. The earlier researches have shown that criteria such as accounting earnings and cash flows are representatives of unobservable aspects of operating performance. The purpose of this study is to indicate whether changes in financial leverage can help us in evaluating performance. This study deals with a different dimension of traditional view that considers financial leverage as a criterion of risk assessment. The method in this research is based on regression analysis to determine the relationship between changes in financial leverage and stock return of a firm regarding as a representative of operating performance of the firm. The statistical population of this study consists of companies accepted in Tehran Stock Exchange in 1378 to 1388. The results of this research indicate that changes in financial leverage provide more information than what is available through traditional criteria. The information content of changes in financial leverage is incremental in comparison with accounting earnings, operating cash flows, and accruals. Although the focus of this study is on the current return, the impact is extended to the next period, because the market does not understand the information content of changes in financial leverage in time.

In this study the effects of financial leverage and operating leverage on cost of capital is studied.Statistical method used in this the study to test the hypotheses is correlation analysis, by calculating correlation coefficient of the variables under study, and testing the hypotheses. The results showed that in Tehran Stock Exchange relationship between capital costs and operating leverage and financial leverage varies from industry to industry. While the capital costs associated with operating leverage and financial leverage is positive in some industries, it is positive and significant in the others, and negative and significant in the remaining. Therefore, findings of the relationship between operating leverage and financial leverage with cost of capital among industries is inconclusive. Also, the finding of this study indicates that the relationship between cost of capital and capital structure (debt to equity) until reaching the optimal point, is a negative and linear. By increasing the amount of debt, cost of capital is reduced and after passing the optimal point (due to excessive use of debt and increasing the risk of bankruptcy), the cost of equity capital with structure has a positive linear relationship. However, the correlation of each company is different.

The main aim of the present study is to examine the effect of financial leverage on operating liquidity in listed companies of Tehran Stock Exchange. Statistical population of the present study is consisted of companies listed on Tehran Stock Exchange during the time period of 2008 to 2014 and sample volume is equal to 118 companies by using screening method and after the elimination of outlaying observations. In this study, financial leverage was taken as independent variable in order to study its effect on current ratio, cash flow conversion cycle margin of the operational cash flow and return on assets. In this study, in which panel data with fixed and random effects were used, results obtained from firm data analysis by using multivariate regression at 95% confidence level indicated that financial leverage has a direct effect on return on assets. It was also indicated that financial leverage has a reverse effect on current ratio and cash flow conversion cycle. In addition financial leverage did not affect on the margin of the operational cash flow.

The aim of this research is study about the different effects of firm size and Industry on firm profitability in Tehran Stock Exchange during 1385 to 1389. The natural logarithm of book value of assets is used as an indicator to measure firm size. Also, the type of industry, the separation of industries with high fixed costs and low on the stock exceeds the number of industries that were concentrated in the categories above. Furthermore profitability is calculated based on three indicators (net operating assets, return on net operating assets and return on operating assets.) the Results of hypothesis tests indicates that there is no significant relationship between high fixed costs and profitability of large companies in various industries. there is no significant relationship between low fixed costs and profitability of small companies in various industries. there is no significant relationship between operating liability leverage and profitability indicators (return on net operating assets and return on operating assets) of small and large companies in industries with low fixed costs (chemical products, cement, lime and gypsum, basic metals and other non metallic mineral products). there is a significant negative relationship between operating liability leverage and two profitability indicators (return on net operating assets and return on operating assets) of small and large companies in industries with high fixed costs (Vehicle and parts manufacturing and Pharma). There is a significant positive relationship between operating liability leverage and return on common equity of small companies in industries with low fixed costs.

The main purpose of this research is the study on effect of Financial and Operating Leverage and Venture Capital on Tobin's Q ratio amongst companies listed in Tehran Stock Exchange. In this research, the Holdings and Investment companies are used as statistical samples and 73 enterprises that are listed in Tehran Stock Exchange within 2001 to 2016 have been studied. The results driven by this research show that Venture Capital, hereafter called "VC", and Operating Leverage, hereafter called "OPL", are positively related to Tobin's Q ratio while Financial Leverage, hereafter called "FL", has negative relation. At the same time, combined variables “FL” and “VC” are negatively correlated with Tobin's Q ratio and combined variable “OPL” and “VC” are neutral on Tobin's Q ratio. The effect estimation of independent variables, namely FL, OPL and VC and control variables, over dependent variable of Tobin's Q ratio is 55%, which is in fact noticeable.

The investigation of stock price crash risk as a significant characteristic of return distribution in capital markets is of particular importance. Accordingly, recent studies have examined various internal, managerial, and external factors affecting this risk and its implications for other variables. The present study focuses on operating leverage as an explanatory variable and aims to investigate its relationship with stock price crash risk in companies listed on the Tehran Stock Exchange (TSE). For this purpose, data from 139 TSE-listed companies spanning the years 2013 to 2022 were collected and analyzed using panel data fixed-effects regression methodology. This research is applied in nature and employs a correlational regression analysis approach. The research hypothesis was tested using multivariate panel regression analysis. The findings demonstrate that companies facing higher stock price crash risk tend to maintain lower levels of operating leverage.