However, it has been recently shown (Gabaix, 2010) that the cross sectional distribution of firms’ size matters a lot for the validity of this assumption. If the distribution of firms’ size has fat tails, then firm-level shocks may propagate to the overall economy. Gabaix indeed showed that the idiosyncratic shocks to the rate of growth in the sales of the largest US firms can predict the one-quarter-ahead growth rate of the US GDP.