Abstract:
Uncertainty appears to vary strongly over time, temporarily rising by up to 200% aroundmajor shocks like the Cuban Missile crisis, the assassination of JFK and 9/11. This paperoffers the first structural framework to analyze uncertainty shocks. I build a model with atime varying second moment, which is numerically solved and estimated using firm leveldata. The parameterized model is then used to simulate a macro uncertainty shock, whichproduces a rapid drop and rebound in employment, investment and productivity, and amoderate loss in GDP. This temporary impact of a second moment shock is different from thetypically persistent impact of a first moment shock, highlighting the importance forpolicymakers of identifying their relative magnitudes in major shocks. The simulation of anuncertainty shock is then compared to actual 9/11 data, displaying a surprisingly good match.