What is the impact of time-varying uncertainty on aggregate economic activity? Using business survey data from the U.S. and Germany in structural vector autoregressions, we find that positive innovations to business uncertainty lead robustly to very prolonged declines in economic activity. In contrast, their high frequency impact is small. We thus find no evidence of the high-frequency wait-and-see effect – large declines of economic activity on impact and fast rebounds – that the recent literature associateswith positive innovations to uncertainty. Rather, positive innovations to business uncertainty have similar effects as negative innovations to business confidence. Once we control for its low frequency impact, we find no statistically or economically significant effect of uncertainty innovations on aggregate activity.