The Dynamics of Inequality

The past forty years have seen a rapid rise in top income inequality in the United States. While there is a large number of existing theories of the Pareto tail of the long‐run income distributions, almost none of these address the fast rise in top inequality observed in the data. We show that standard theories, which build on a random growth mechanism, generate transition dynamics that are too slow relative to those observed in the data. We then suggest two parsimonious deviations from the canonical model that can explain such changes: “scale dependence” that may arise from changes in skill prices, and “type dependence,” that is, the presence of some “high‐growth types.” These deviations are consistent with theories in which the increase in top income inequality is driven by the rise of “superstar” entrepreneurs or managers.     

DO PRICES TRANSMIT RATIONALLY EXPECTED INFORMATION?

A simple model with asymmetric information, in which inventory holders or traders submit demand curves to an auctioneer, has a unique partially revealing equilibrium. We wonder whether the agents can plausibly coordinate on this equilibrium through “eductive” reasoning relying on common knowledge. The analysis stresses the role of two effects, sensitivity and amplification, whose product should be small enough. The property is obtained whenever the equilibrium excess demand is steep enough, i.e., when the search for information does not distort demand too much. Neither the influence of the number of informed agents nor that of noise trading are monotonic. Real‐time learning has strikingly different features. (JEL: D82, D84)