درخت حوزه‌های تخصصی

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.

Ibn Abbas is one of the most famous exegete companions known as the grandmaster of the Meccan school of interpretation. His prominent position is due to the large number of interpretive narrations quoted from him. Numerous works in the interpretation of the Qur'an are attributed to him, among which some works are more famous due to the possibility of his own writing or direct quotation from him or their important contents. One of the famous exegetical works attributed to Ibn Abbas is called “Tanwīr al-Miqbās.” According to the content evaluation, the authenticity of the attribution of this work to Ibn Abbas cannot be accepted; The most important reasons in terms of content are as follows: problems in the number of words and letters of some surahs, the existence of words indicating quotations from other companions and followers, the existence of later terms and the existence of late sectarian and theological evidence. Similarly, both documentary