Employment growth is strongly predicted by smaller average establishment size, both across cities and across industries within cities, but there is little consensus on why this relationship exists. Traditional economic explanations emphasize factors that reduce entry costs or raise...

We build a model of firm-level innovation, productivity growth and reallocation featuring endogenous entry and exit. A new and central economic force is the selection between high- and low-type firms, which differ in terms of their innovative capacity. We estimate the parameters of the model...

How do innovative firms react when existing products experience negative shocks? We explore this question with detailed project-level data from drug development firms. Using FDA Public Health Advisories as idiosyncratic negative shocks to approved drugs, we first examine how drug makers react...