مهدی درویشان

Choosing the proper investment mechanism is one of the main tasks of any investor that requires careful analysis and research on all available information. Since no investor exactly knows whether his or her expectations for a particular stock return will be met, they need to build their strategy in such a way as to eliminate as much damage as possible in the event of an adverse outcome. This study aims to predict the optimal portfolio using Algorithm Analysis Systems. In this regard, 98 firms listed on the Tehran Stock Exchange were examined in 2015-2019. Then, random portfolios were selected to test the research hypotheses by separating value stocks and growth stocks. For analysis, two algorithms of Support Vector Machines and an Adaptive Neuro-Fuzzy Inference System were used to select the most desirable portfolio. According to the support vector machine algorithm analysis, the results confirm the difference between the Sortino and Marquitz portfolios. To build their portfolios, decision-makers often rely on growth stocks which can boost their expected returns. Therefore, recognizing the analytical nature of portfolio formation in specialized areas can help improve investment analysis and pave the way for higher returns.

Managers are responsible for providing financial statements and they might try to make a good picture of their firm's conditions. Therefore, they try to delay the disclosure of bad news and release the good news as soon as possible. The ten-dency of managers toward hiding bad news increases the stock price crash risk. The protection of investor is one of the factors that can prevent from falling stock price, because it restricts the managers and majority shareholders in frauding and hiding bad news. Thus, the main purpose of the present research is to study the effect of investor protection on future stock price crash risk. In this research, 89 companies from listed companies in Tehran Stock Exchange during 2011-2017 were tested. The results obtained from the research's hypothesis test showed that protecting the rights of investors has a negative effect on the stock price crash risk. In fact it can be concluded that with the increase of the investor protection, the firms are obligated to disclose the high-quality accounting information and present more transparent financial reporting, as a result, the information asym-metry will be reduced and by creating a flow of information between the manag-ers and the investors and thus failure to accumulate bad news in the company, the risk of the stock price crash will be also reduced.