درخت حوزه‌های تخصصی

The purpose of this paper is to analyze the relationship between default risk and momentum effect using data from companies listed on Tehran Stock Exchange.To calculate default risk,we used Black-Scholes-Merton (BSM) option pricing model. To describe momentum effect, by determining the formation period to be 6 months, and the holding period to be 3,6, or 12 months, we firstlyexamined the profitability of short term (3/6), midterm (6/6), and long term (12/6) momentum strategies and found that during 2010-2015 time period, only midterm momentum strategy is profitable.Then,we showedthere is no relationship between default risk andmomentum effect.

Market efficiency paradigm and time patterns concerned, as "calendar anomalies" is a contradictory issue for researches. TSE's market participants have a negative understanding of the 6th and 12th month of the fiscal year and this issue is rooted in the obliged credit settlement of the brokerage industry at the year-end. The purpose of this study is to investigate the TSE's total return before and after brokerage firms' year-end. Using GARCH-PQ, and data of market index in periods between 1390 and 1396, we concluded that periods of1st to 22ndof 6thand 12th months,and 22nd to the end of 6th and 12th months, have respectivelynegative and positive effectson TSE's stock index.

This study aims to investigate the correlation between the diversification and accruals quality (AQ) in Iran’s mutual funds considering two main hypotheses and four sub-hypotheses. This research investigates the effects of cases such as beta of the company, the company's return on assets, debt ratio of company, firm's size, and accrual quality on the company's cost of capital and considers the effect of mutual funds’ diversification on decreasing information risk calculated through accruals quality in Tehran Stock Exchange (TSE) and Iran Farabourse listed companies. This research investigates 42 mutual funds from 2009 to 2013. Furthermore, the financial data of companies is considered for 20 years up to 2013 in order to calculate the accruals quality. The research results indicate that the factors such as the company's beta, the company's return on assets, and the ratio of firm's debt have direct correlation with cost of capital and this indicates that the increased risk in the form of beta and debt ratio increases the investors' expected return. However, the firm's size is inversely correlated with the cost of capital indicating that the increased firm's size provides the possibility of borrowing and bargaining at lower costs for companies. Furthermore, diversification in mutual funds results in lowering information risk caused by low accrual quality. Accordingly, the result of this research can help the mutual funds’ managers and investment companies to better manage their investments

Optimal Portfolio Selection is one of the most important issues in the field of financial research. In the present study, we try to compare four various different models, which optimize three-objective portfolios using “Postmodern Portfolio Optimization Methods”, and then to solve them. These modeling approaches take into account both multidimensional nature of the portfolio selection problem and requirements imposed by investors. Concretely different models optimize the expected return, the down side risk, skewness and kurtosis given portfolio, taking into account budget, bounds and cardinality constrains. The quantification of uncertainty of the future returns on a given portfolio is approximated by means of LR-fuzzy numbers, while the moments of its returns are evaluated using possibility theory. In order to analyze the efficient portfolio, which optimize three criteria simultaneously, we build a new NSGAII algorithm, and then find the best portfolio with most Sortio ratio from the gained Pareto frontier. Thus, in this paper we choose 153 different shares from different industries and find their daily return for ten years from April of 2006 till March of 2017 and then we calculate their monthly return, downside risk, skewness, kurtosis and all of their fuzzy moments. After designing the four models and specific algorithm, we solve all of the four models for ten times and after collection of a table of the answers, compare all of them with Treyner ratio. At last, we find that using fuzzy and possibistic theory make higher return and better utilized portfolios.

The present study investigated weak-form market information efficiency in Tehran security exchange (TSE) as an emerging market and in Dow Jones United States security exchange (DJUS) as a developed market based on random walk model. In each market, the random walk model was examined using daily and monthly returns of a set of indices. The results of the parametric and non-parametric tests indicated that the daily returns are not independent and identically distributed in TSE. Moreover, according to the results of the variance ratio test, a trending behavior in daily returns and mean-reversion behavior in monthly returns were observed. In DJUS, however, the daily returns were found to be independent and identically distributed and the results of variance ratio test did not confirm that the returns follow a particular pattern in this market.