seyyed kazem ebrahimi

The optimizing the investment portfolio is considered one of the most important topics in capital management. Our goal in this article is to design an optimal portfolio selection model based on the Minimum Spanning Tree method in the Iranian stock market. Designing and compiling a portfolio selection model includes two It is the basic stage. The first stage of choosing the investment portfolio was done using five criteria of centrality, betweenness, distance from the center, distance from correlation and distance from the distance criterion. The result of this work is the formation of two central and peripheral portfolios, respectively. It was the central portfolio and peripheral portfolio the network. In the second step, using risk and return measurement criteria, selected portfolios were optimized and risk managed. At the end, the extracted portfolios were evaluated with the total index and one share of the portfolio for a period of 200 days. The results showed that both portfolios had higher efficiency according to the market conditions. As expected, during the growth of the market, the surrounding portfolio recorded a higher return compared to the market.

This study investigated the relations between governmental ownership, political relations and related party transactions on external financing and investment. Sampling was done by systematic screening method from companies listed on the Tehran Stock Exchange, 102 companies were selected during the years 2014-2020. The research hypotheses were tested using a multiple regression model with fixed effects. Governmental ownership and political connections have a negative and significant relation with external financing, and related party transactions have a positive and significant relation with external financing. But Governmental ownership, political connections, and related party transactions are not related to investment. government-owned companies use government funding instead of external financing. Corporate political connections are not necessarily to attract external funding. related party transactions can be done with the aim of optimally allocating internal resources, reducing transaction costs, and improving asset returns among group companies. governmental ownership is a tool for achieving government goals. Investment is also being revised as economic conditions change. Political connections can lead to the distortion or induction of inappropriate investment decisions. The lack of a relation between related party transactions and investment confirms the conflict of interest and the abuse of the company's resources through them.

In economic systems based on relationships, political communication is one of the most important sources of value for companies with these relationships. One of the solutions for the government to control the country's economy is to influence the enterprises. Government influence in economic units is created through the relations of politicians or state ownership. Establishing and maintaining relationships between companies and government is usually accompanied by competitive advantages, companies with more political relationships are more likely to access capital resources and other benefits through their communications, which rely heavily on high-quality financial reporting. The goal of some corporate executives to communicate is to eliminate financial constraints with the least cost. The purpose of this study was to identify the effect of the political relations of Tehran Stock Exchange companies on the conservatism of profit and loss and the cost of debt. The method of this research is correlation and based on multivariate regression. To test the hypotheses, a sample of 102 companies was used during the five-year period from 2013 to 2017. The findings of the research show that the political relations in companies have a negative and significant effect on the conservatism of profit and loss. Political relationships also have a negative and significant impact on corporate debt costs.

This study aimed to examine the effects of Political connections on accounting conservatism, investment efficiency and cost of financing in the companies listed in the Tehran Stock Exchange during the period 2013 to 2017.

Data was collected using document mining method and referring to the databases, and data analysis method was inferential. Eviews software was used to provide estimates for the concerning variables. The panel data model was used to test the research hypotheses.

The findings of the research indicated that political connections in the the companies have negative and significant effects on accounting conservatism, and have negative and significant effects on cost of financing. Also, according to the research findings, company's political connections do not have significant impacts on capital efficiency.

As the debt ratio of corporation increases, the level of conservatism decreases. This means that companies that have political connections are less conservative than other companies.

Todays, the issue of earnings management, has attracted the attention of many researchers in such a way that the researchers follow more their reasons and motivations in earnings management. One of the factors on Earnings management, more confidence in management. Overconfidence is an important feature of managers who are optimism about future earnings and cash flows and have a positive view of potential risk and return. Hence, we are going to investigate the effect of manager's overconfidence on earnings management. To do so, the financial data between the years 2010 to 2015 of listed companies in Tehran stock exchange was sampled with systematic deletion analysis in which 107 companies were sampled. To analyze the research hypotheses, multiple regression with the use of panel data was appliedThe results. The results showed that the more trust management andReal earnings management standards. There is a significant positive relationship...

The current paper intends to analyze the effects of accountings quality on the amount of information asymmetry, considering the life cycle of accepted companies in in Tehran stock exchange. In this regard, between 1388 and 1391, 117 companies were chosen as samples. Based on the provided model by Anthony and Ramesh and by the use of three variables; the sales growth, the ratio of dividend earnings and the capital expenditure, the members of the sample were divided into three stages; growth, maturity and decline. In this research, the quality of accountings information is considered synonymous with the quality of earning. The modulus of errors caused by the estimation of accruals by Regression line provided by Dechow and Dichev model as a parameter to assess the quality of earnings. In order to test the hypothesis, the multivariate regression technique by Cross-sectional data was applied. At first, the companies are tested in general and the evidence show that there is a significant positive correlation between earnings quality and information asymmetry. Then, the research model is tested separately for each one of the life cycle stages and the findings indicate a significant positive correlation in the growth stage. But there is no significant relationship between earnings quality and information asymmetry in maturity and decline stages.