Consistent with this premise, the empirical analysis in this paper examines whether idiosyncratic volatility is related to earnings non commonality. We show the existence of a significant positive relationship between idiosyncratic volatility and earnings non commonality. In addition, low earnings non commonality reduces idiosyncratic volatility. Several robustness tests performed validate these findings. We also rule out that earnings non commonality is an indicator of market power or in novativeness. Prior studies suggest that idiosyncratic volatility increases because of more active retail investors, low-priced stocks, and the listing of riskier firms. Our results remain robust after considering the effects of retail investors’ influences, institutional ownership, and firm riskiness. Our paper contributes to the literature by suggesting another possible explanation for the recent increase in idiosyncratic volatility as pointed out by Campbell et al. (2001), and aids in a better understanding of the asset prizing puzzle that has intrigued the researchers of late. The robustness tests we conduct show that market power and in novativeness previously suggested in the literature as possible causes of the increased idiosyncratic volatility are not significant in explaining idiosyncratic volatility in the presence of earnings non commonality as an explanatory variable. On the practical front, the paper identifies an important determinant of idiosyncratic volatility which has important ramifications for portfolio diversification, arbitrageurs, and pricing of employee stock options.