We characterize a firm as a nexus of activities and projects with their associated cash flow distributions across states of the world and time periods. We propose a characterization of the firm where variations in the market price of risk induce adjustments in the value-maximizing combination of...

In this paper, we formally show that the cross-sectional variance of stock returns is a consistent and asymptotically efficient estimator for aggregate idiosyncratic volatility. This measure has two key advantages: it is model-free and observable at any frequency. Previous approaches have used...