Essays on firms, aggregate uncertainty, and the labor market[Entreprises, incertitude agrégée et marché du travail]

This thesis is comprised of three chapters that revolve around two main themes:the micro economic incidence of macro shocks and the role of firms in determining labor market outcomes. In the first chapter I provide new evidence on the cyclical dynamics of firms. I show that firms expecting to lose market share in the futureare hit the hardest during economic downturns. This heterogeneous sensitivity provides a new rationale for the observed counter-cyclical dispersion in firms'growth rates and has implications for the dynamics of aggregate employment. The second chapter studies the role of income tax progressivity in reallocating income risk across heterogeneous workers and stabilizing the economy. We show that eliminating income tax progressivity in Italy would come at the expense of the majority of the work force. The current system of marginal tax rates is effective atreallocating cyclical income risk from low to high wage workers and reducesaggregate employment volatility compared to a counter-factual flat rate system.The third chapter considers the internal hierarchical structure of a firm and its rolein determining wages and internal promotions. We focus in particular on the rolethat internal hierarchies play in propagating gender differences in representation and pay. We study the effect of a change in the gender composition at the top afirm's internal hierarchy on workers further down the organizational ladder and findsome evidence of an effect only on layers close to the top.