This paper is aimed to investigate the relation between opacity, synchronicity and crash risk. It is expected opacity represent lower firm specific information and resulted in higher synchronicity and crash risk. In order to this aim, a sample composed of listed firms in Tehran Stock Exchange during 1381 to 1393 is examined. To investigate above relations, methods including logistic, panel data and Fama-Macbethregressions are used. The research findings confirm that crash cannot be attributed to opacity. Lack of relation between opacity and jump is recognized. Also, it cannot be claimed that opacity result in lower firm specific information and higher synchronicity. Latter findings are not sensitive to synchronicity and crash measures.

The purpose of this research was to investigate the role of uncertainty in monetary policies on the synchronicity of company’, s stock prices. The statistical population of the research consists of all the companies listed in Tehran Stock Exchange between 2010 and 2019, of which 118 companies have been studied as a statistical sample of the research. The research data were analyzed using regression models using the pooled data method. In order to measure the uncertainty in monetary policies, two methods based on the entropy of exchange rate values and also fitting the GARCH heterogeneous variance model were used. The findings of the regression models showed that the increase in uncertainty in the monetary policies of each period under both the entropy criteria and the GARCH model has an adverse effect on the synchronicity of the stock prices in the future period. Therefore, the degree of stock prices synchronicity in each period can be predicted by relying on the uncertainty of monetary policies of the past period and the company's financial ratios. Also, the results showed that managers' strategies in order to reduce the debt ratio, increase cash retention and under investment to deal with the uncertainty caused by monetary policies, have a moderating effect on the relationship between this uncertainty and price synchronicity and strengthen the size of its effect on the synchronicity of the stock prices in the future period.

Investor sentiment about the capital market can play an important role in stock price trends, market transactions, and especially on the stock return synchronicity. The entry of many Individual investors who do not have enough information about investment, the study of this issue has made more important. To this end, in this research we investigate the relationship between investor sentiment and stock return synchronicity in Tehran Stock Exchange, by using the financial data of 167 firms listed on Tehran Stock Exchange from 15 various industries during ten years from March 2010 to March 2020. We use the Baker-Wurgler (2006) sentiment index as our primary measure of investor sentiment that Measured by principal component analysis. Also, three different methods have been used to measure the stock return synchronicity: the Mork model, the Carhart four-factor model and the Fama and French five-factor model. The results show that the Investors sentiment significantly affect on increasing stock return synchronicity. The findings also showed that the coefficients of positive and negative sentiment are not significantly different and as a result, positive and negative sentiment are symmetrically affecting the increase in stock return synchronicity.

The purpose of this research is to study studying the relationship between stock price synchronicity and tails of return distribution at Tehran Stock Exchange. The sample consists of 118 companies that have been chosen from among compaines listed in Tehran Stock Exchange during the period of 2010-2014, and hypothesis testing has been done with multiple regression based on panel data. The results of hypothesis testing show that firms with high stock price synchronicity have higher probability of generating positive tails than firms with low synchronicity, and also there is positive relation between stock price synchronicity and skewness. Investors of stocks with hig price synchronicity have lower reaction to bad news in respect to stocks with low price synchronicity. High stock price synchronicity show that market information reflected on stock return is more, and investors suffer only systematic risk. Therefore, it is suggested that investors in Tehran Stock Exchange invest on stocks with higher stock price synchronicity and with higher information transparency.

The purpose of this research is to determine the effect of financial statements comparability as one of the qualitative characteristics of financial reporting on stock price synchronicity. Stock price synchronicity is a criterion that has been used inversely to measure the information content of stock prices. In order to attain the research purpose, 86 companies among the listed companies in Tehran Stock Exchange during the years 1385 to 1392 (2007-2014) were selected as statistical samples. For analyzing data and testing hypotheses, multi variable regression model with compound data and mean comparison test have been used. Findings of research signify that financial statement comparability has a significant negative impact on stock price synchronicity. The results also show that in firms with lower synchronicity, information asymmetryis lower. Based on this finding, it can be concluded that financial statements comparability causes the higher level of firm-specific information to be reflected in stock prices.

Stock price synchronicity is a relative measure of companyspecific information in comparison with the market and industry data that is reflected in stock prices; therefore, it is inverse to transparency. The purpose of this paper is to investigate the effect of managerial optimism on stock price synchronicity. To achieve this goal, the satistical sample of this study consists of 112 firms listed on the Tehran Stock Exchange during 2010-2016. The Piotroski & Roulstone's model (2005) was used to measure stock price synchronicity and managerial optimism has been measured based on three criteria including accuracy of profit prediction by managers, the surplus of capital expenditures, and the remainder of the company’ s growth model. The findings showed that optimism (surplus capital expenditures) has a positive and significant effect on synchronization. But There was no significant effect on the other two optimistic proxies.

Objective: Pyramidal ownership structures and cross-ownership are common phenomena in developing economies. These structures result in a divergence between voting rights and cash flow rights on the one hand, and create internal capital markets through which firms can raise capital internally instead of going to the public market when they need additional financing. In the present study, the effects of firm interlock and stock price synchronicity in Iran Stock Market was investigated. Methods: We used a unique data set containing stock ownership and directors of all companies listed on the Tehran Stock Exchange considering three definitions of management, stockholding, and ownership and examined interlock through both equity ties and interlocking directors. Results: We found that over 40 percent of all listed companies belong to networks of interconnected companies and there was a significantly positive relationship between being a member in each of these networks and the profitability of the firm alongside other colleagues. We also documented a complex set of networks among listed and unlisted companies, which have not been previously documented. We further find that pairwise interlocks through equity ties – either direct ownership or common owner – are correlated with higher stock price synchronicity, whereas common directorship is not linked to return co-movement. We can also claim that the effect is decreasing as firms become farther away from each other within a network. Conclusion: The results show that firm interlock, particularly through cross holdings and common ownership, can increase stock price synchronicity.

The aim of this study was to evaluate the effectiveness and impact of free cash flow and growth on stock return synchronicity of companies listed on the Tehran Stock Exchange. The main hypothesis of this study is that companies with low growth and high cash flow concurrency higher stock returns. To test the hypothesis and achieve the objectives of the study, 101 samples companies (505 years - the company) that in the years 2010 to 2015 have been accepted in Tehran Stock Exchange, the National systematic sampling were selected. Statistical methods for the main hypothesis proposed in this research model on panel data regression with random effects is panel. We find that Low-growth firms with high free cash flow have a higher stock return synchronicity.The research findings show that between free cash flow and growth of company with stock returns synchronicity there is a significant concurrency and about 49% of the variance in stock returns synchronicity expressed by these variables.

Block trading is used by investors in the capital market because it provides company-specific information, which is a tool for optimal stock pricing. Additionally, the media can bring the interests of managers and shareholders closer together by publishing company-specific news, thereby reducing information asymmetry, increasing stock price awareness, and decreasing stock price coincidence. Therefore, the purpose of this study is to investigate the moderating role of media coverage in the effect of block trading on stock price synchronicity. The statistical population of this research consists of companies listed on the Tehran Stock Exchange from 1393 to 1401, which were selected through systematic deletion of data from 100 companies, including 11, 237 block transactions for review, experience, and analysis. The results of the Multivariate regression model based on composite data showed that the number and block trading ratio have a positive effect on stock price synchrony. Moreover, media coverage as a moderator variable in the effect of block trading ratio has a negative effect on stock price synchrony. These findings emphasize the inefficiency and lack of transparency of information in the Iranian stock market, which prevents the timely incorporation of company-specific information into stock prices.