درخت حوزه‌های تخصصی

The Iranian economy in recent years is due to the development of economic sanctions, a sharp decline in the price of oil and the deficit resulting from revenue - dependent on oil revenues and the trend towards tax revenues. While comparing the volume of the Iranian economy with the amount of tax income indicates the existence of a relatively significant tax gap. The tax gap is the difference between the collected taxes and the tax required by the law. The purpose of this study is to answer the question whether corporate governance is effective and strong on the relation between tax gap and future earnings changes? The statistical population of the research in Tehran Stock Exchange (TSE) firms and statistical sample consists of 120 companies in the period of 2007-2017. In order to test the hypotheses, multivariate regression using mixed data - data approach has been used. The results indicate that there is a significant inverse relationship between the tax gap and future earnings changes. It can be argued that increasing the difference between earnings accounting earnings can be associated with decreasing interest in the next year and less stability. On the other hand, significant positive relation between corporate governance is efficient and strong with future earnings changes. because corporate governance will ultimately lead to more sustainable future gains due to the decline of discretionary accruals in discretionary accruals. It is also reinforced by the effect of the tax gap on future earnings changes in firms that have efficient corporate governance, and this effect is only seen for a year later. And is not effective for the second and third years.

In recent years, authors have focused on modeling and forecasting volatility in financial series it is crucial for the characterization of markets, portfolio optimization and asset valuation. One of the most used methods to forecast market volatility is the linear regression. Nonetheless, the errors in prediction using this approach are often quite high. Hence, continued research is conducted to improve forecasting models employing a variety of techniques. In this paper, we extend the field of expert systems, forecasting, and model by applying an Artificial Neural Network. ANN model is applied to forecast market volatility. The results show an overall improvement in forecasting using the neural network as compared to linear regression method.

The gaining returns in line with risks is always a major concern for market play-ers. This study compared the selection of stock portfolios based on the strategy of buying and retaining winning stocks and the purchase strategy based on the level of investment risks. In this study, the two-step optimization algorithms NSGA-II and SPEA-II were used to optimize the stock portfolios. In order to determine the winning algorithm, the performance indexes, Set coverage and the Mean Ideal Distance were used. Finally, the active shares of 50 Tehran Stock Exchange com-panies were analysed (2007-2016). The results indicate that the SPEA-II algo-rithm can perform optimization and achieve a better performance than the NSGA-II. This algorithm could achieve better outcomes than the winning strategy during the selection period based on the risk-taking strategies in different months

Fraudulent financial reporting has been one of the most sensitive issues on the business world. Financial statements that conceal the company's facts have caused great losses to its stakeholders. The ranking of companies based on fraudulent financial reporting is one of the key issues for performance analysis. This study, by using financial variables and the data envelopment analysis methodology, ranked the pharmaceutical companies listed on the Tehran Stock Exchange in terms of fraudulent financial reporting. The data and theoretical framework of the research are based on library studies and data analysis has been done based on the data envelopment analysis model. The results of this study indicate that the most manipulation of profits in 2015 was in the Daru Amin and Faravordehaye Tazrighi companies, as well as Iran Daru and Sina Daru in 2016. This will lead to the companies being ranked at the highest level of fraudulent financial reporting.

Recently, understanding the anomalies in financial markets have severely chal-lenged the efficient market hypothesis (EMH). The price momentum is one of the anomalies described as the unexplained short-term return by Fama and French (1996). The present research strives for modeling the price momentum of winner stock in the Iranian capital market. The grounded theory method was used to explain this phenomenon. To this end, in-depth interviews were held with 32 experts operating in the professional and academic fields in 2018. The collected data was encoded in three steps, and the results were presented as a conceptual paradigm. The research findings identified the momentum causal factors in the behavioral level, the background factors in the social, macroeconomics, and mar-ket levels, the intervening factors in the global economics, macroeconomics, mar-ket, and company levels, and the strategies in the social, macroeconomics, market, the investment and finances institutions, and consequences factors in market level. The research findings suggest that the winner stock price momentum phenomenon should not be considered a speculation opportunity. Rather, it is an anomaly that has to be regulated with the proposed strategies according to the experts. The consequences of the adoption of these strategies include the stable and normal income for the market actors, the decrease in the loss inflicted on natural persons due to the market volatility, the management of anomalies, more effective attrac-tion and allocation of liquid capitals, the reduced credit risk of brokerages, and the acceleration of liquidation in the market.

In this study, I try to examine the effect of environmental sustainability on CEO risk taking. Prior research, however, has struggled to establish this relation empirically; moreover, some evidence points to the possibility that the CEO risk appetite is lower for firms with sustainable environment. The opportunistic approach of managers leads to decisions about personal interests and imposing costs on shareholders by decreasing risk taking. In order to investigate the issue, data on companies listed in Tehran Stock Exchange for the period 2008-2018 were extracted and a panel regression model was used to test the research hypotheses. Consistent with expected relation between CEO risk taking and the environmental sustainability, It decreases with respect to CEO opportunistic approach. Managers may benefit from increased fluctuations in risk orientation, but are more sensitive than shareholders and have less restrictive choice that avoids higher risk.