We show how real and financial frictions amplify, prolong, and propagate the negative impact of uncertainty shocks. We use a novel instrumentation strategy to address endogeneity in estimating the impact of uncertainty by exploiting differential firm exposure to exchange rate, policy, and energy price volatility. We show that financially constrained firms cut investment more than unconstrained firms following an uncertainty shock. We then build a general equilibrium heterogeneous firms model with real and financial frictions, finding that financial frictions (i) amplify uncertainty shocks by doubling their impact on output; (ii) increase persistence by doubling the duration of the drop; and (iii) propagate uncertainty shocks by spreading their impact onto financial variables.

Uncertainty rises in recessions and falls in booms. But what is the causal relationship? We construct cross-country panel data on stock market returns to proxy for first- and second-moment shocks and instrument these with natural disasters, terrorist attacks, and political shocks. Our IV regression results reveal a robust negative short-term impact of second moments (uncertainty) on growth. Employing multiple vector autoregression estimation approaches, relying on a range of identifying assumptions, also reveals a negative impact of uncertainty on growth. Finally, we show that these results are reproducible in a conventional micro–macro business cycle model with time-varying uncertainty.