This paper shows that news shocks amplify macroeconomic volatility in any purely forward-looking model, whereas results are ambiguous when including a backward-looking component. We also investigate numerically the volatility effects of news shocks within the Smets and Wouters (2003) model.

Rational expectations models with news shocks may generate moving average representation that are nonfundamental. The nonfundamentalness typically arises from the lag polynomial associated with news shocks. This paper provides an exact solution formula for this special type of polynomial and...