مطالب

The gaining returns in line with risks is always a major concern for market play-ers. This study compared the selection of stock portfolios based on the strategy of buying and retaining winning stocks and the purchase strategy based on the level of investment risks. In this study, the two-step optimization algorithms NSGA-II and SPEA-II were used to optimize the stock portfolios. In order to determine the winning algorithm, the performance indexes, Set coverage and the Mean Ideal Distance were used. Finally, the active shares of 50 Tehran Stock Exchange com-panies were analysed (2007-2016). The results indicate that the SPEA-II algo-rithm can perform optimization and achieve a better performance than the NSGA-II. This algorithm could achieve better outcomes than the winning strategy during the selection period based on the risk-taking strategies in different months

Fraudulent financial reporting has been one of the most sensitive issues on the business world. Financial statements that conceal the company's facts have caused great losses to its stakeholders. The ranking of companies based on fraudulent financial reporting is one of the key issues for performance analysis. This study, by using financial variables and the data envelopment analysis methodology, ranked the pharmaceutical companies listed on the Tehran Stock Exchange in terms of fraudulent financial reporting. The data and theoretical framework of the research are based on library studies and data analysis has been done based on the data envelopment analysis model. The results of this study indicate that the most manipulation of profits in 2015 was in the Daru Amin and Faravordehaye Tazrighi companies, as well as Iran Daru and Sina Daru in 2016. This will lead to the companies being ranked at the highest level of fraudulent financial reporting.

Recently, understanding the anomalies in financial markets have severely chal-lenged the efficient market hypothesis (EMH). The price momentum is one of the anomalies described as the unexplained short-term return by Fama and French (1996). The present research strives for modeling the price momentum of winner stock in the Iranian capital market. The grounded theory method was used to explain this phenomenon. To this end, in-depth interviews were held with 32 experts operating in the professional and academic fields in 2018. The collected data was encoded in three steps, and the results were presented as a conceptual paradigm. The research findings identified the momentum causal factors in the behavioral level, the background factors in the social, macroeconomics, and mar-ket levels, the intervening factors in the global economics, macroeconomics, mar-ket, and company levels, and the strategies in the social, macroeconomics, market, the investment and finances institutions, and consequences factors in market level. The research findings suggest that the winner stock price momentum phenomenon should not be considered a speculation opportunity. Rather, it is an anomaly that has to be regulated with the proposed strategies according to the experts. The consequences of the adoption of these strategies include the stable and normal income for the market actors, the decrease in the loss inflicted on natural persons due to the market volatility, the management of anomalies, more effective attrac-tion and allocation of liquid capitals, the reduced credit risk of brokerages, and the acceleration of liquidation in the market.