درخت حوزه‌های تخصصی

<span>Corporate social responsibility (CSR) is a fundamental factor for the survival of any organization. Companies and institutions are active in a society that provides them various opportunities to earn profits and realize their goals. The increasing importance of corporate social responsibility and the costs required by companies to operate and participate in these issue has led to the purpose of this study to investigate the impact of corporate social responsibility on the managers' behaviors in companies listed on the Tehran Stock Exchange. This study is based on purpose, application and data analysis in the field of causal descriptive studies. In this study, the reflection of managers’ myopic and optimistic behaviors is considered as managers' behaviors. Therefore, two hypotheses were developed to investigate this issue, and data from 174 listed companies were analyzed from 2008 to 2018. The regression model of the research was evaluated using a panel data method with a fixed-effects approach and logistic regression method. The result showed that the fulfillment of corporate social responsibility has a significant negative effect on the optimistic behavior of managers and decreases this type of behavior by managers. On the other hand, the results confirmed that accomplishing corporate social responsibility does not have a significant effect on managers' myopic behavior.

Value at Risk model based on a switching regime approach was used in this study to optimize portfolios consisting of industry index (petroleum products, investment, chemical products, and metal products). For this purpose, the VaR of returns on index should first be extracted through parametric models of the (GARCH) family in each of the above industries by using regime transitions. After the risk of return on index is obtained for each industry, the optimal portfolio is created in the next step based on VaR minimization, and the optimal value of each industry is determined in the portfolio. According to the results, (MRS-FIEGARCH) model had no superiority in VaR estimation over the other parametric models of the GARCH family. In fact (MS-EGARCH-t) was introduced as the optimal model. Among the designated industries, returns on indices followed regime transitions only in chemical products and investment by showing asymmetric reactions to external shocks. Moreover, the optimal weights were on the rise in the industries where VaR decreased over time, whereas the optimal weight of the portfolio decreased in the industries where VaR increased over time. The higher share of an optimal portfolio belonged to the industries where stock returns had lower rates of VaR. The risk-return-ratio was employed to show that the optimal portfolio with a risk rate was measured by considering the switching regime was superior over the optimal portfolio with a risk rate extracted without considering the switching effects. To create an optimal portfolio, it is then recommended to make investments in the industries characterized by higher stability in prices and lower fluctuations in stock returns in the long run. This approach can be employed to obtain the best results from optimal portfolio preparation in the worst-case scenario of the market fluctuations.