NBER Working Papers by Sunil Mulani

This paper presents an endogenous growth model that explains the evolution of the first and second moments of productivity growth at the aggregate and firm level during the post-war period. Growth is driven by the development of both (i) idiosyncratic R&D innovations and (ii) general innovations that can be freely adopted by many firms. Firm-level volatility is affected primarily by the Schumpeterian dynamics associated with the development of R&D innovations. On the other hand, the variance of aggregate productivity growth is determined mainly by the arrival rate of general innovations. Ceteris paribus, the share of resources spent on development of general innovations increases with the stability of the market share of the industry leader. As market shares become less persistent, the mod...

This paper documents the diverging trends in volatility of the growth rate of sales at the aggregate and firm level. We establish that the upward trend in micro volatility is not simply driven by a compositional bias in the sample studied. We argue that this new fact sheds some shadows on the proposed explanations for the decline in aggregate volatility and that, given the symmetry of the diverging trends at the micro and macro level, a common explanation is likely. We conclude by describing one such theory.