Embrace or Fear Uncertainty: Growth Options, Limited Risk Sharing, and Asset Prices

March 2017

I show that the effect of uncertainty shocks on asset prices and macroeconomic dynamics depends on the degree of risk sharing in the economy and the origin of uncertainty. I develop a general equilibrium model with imperfect risk sharing and two sources of uncertainty shocks: (i) cash-flow uncertainty shocks, which affect the idiosyncratic volatility of firms’ productivity, and (ii) growth uncertainty shocks, which affect the idiosyncratic variability of firms’ investment opportunities. My model deviates from the neoclassical setting in one respect: firms’ investment policies are set by the experts who are subject to a moral hazard problem and thus must maintain an undiversified ownership stake in the firm. As a result, risk sharing between experts and other investors is imperfect. Limited risk sharing distorts equilibrium investment choices, firm valuation, and prices of risk in equilibrium relative to the frictionless benchmark. In the calibrated model, the risk premium on growth uncertainty shocks is negative under poor risk sharing conditions and positive otherwise. Moreover, the cross-sectional spread in valuations between value and growth stocks loads positively on the growth uncertainty shocks under poor risk sharing conditions and negatively otherwise. Empirical tests support these predictions of the model.