An analysis of Idiosyncratic Volatility Anomaly

This paper aims to investigate the pricing of idiosyncratic volatility in the Tehran Stock Exchange. Moreover, it examines whether the explanations proposed by previous studies for the idiosyncratic volatility anomaly in the developed markets can be applied to the evidence obtained from the Tehran Stock Exchange?

the sample includes thefirmsthat have positive book values, the non-financial intermediaries, and the firms with the fiscal year ending on the last day of March. Tocalculate idiosyncratic volatility, the firms with trading days less than onece each month are excluded. The final sample consists of 48firmslisted in the Tehran Stock Exchange, over the period from 2008 to 2019. The hypothesis is examined by using the three-factor Fama andFrench (1993) model, the one-way portfolio sorting approach on idiosyncratic volatility, the two-way portfolio sorting on idiosyncratic volatility, and the five risk factor, and Fama and MacBeth (1973) cross-sectional regressions method.

suggests a positive and statistically significant relationship between the idiosyncratic volatility and the future stock returns. This result is persistent after controlling for the Fama-French three risk factors (excess market return, SMB, and HML), the short-term reversal factor, the preference for lottery-type stocks, and the momentum factor (Carhart, 1997).

there is no evidence of the idiosyncratic volatility anomaly in the Tehran Stock Exchange; therefore, the investors should take into account the idiosyncratic volatility in their investment decisions. Furthermore, none of the explanations in the literature can explain the idiosyncratic volatility positive premium on the Tehran Stock Exchange.

the idiosyncratic volatility anomaly was investigated mainly for developed markets and other developing countries. Moreover, the existing explanations about the idiosyncratic volatility anomaly have not yet been examined for the Tehran Stock Exchange. Therefore, this study aims to fill this gap to extend the literature on the emerging Tehran Stock Exchange.