Pierre-Louis Lions

College de France
Rue d’Ulm 3
75005 Paris Cedex 05, France

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Institutional Affiliation: College de France

NBER Working Papers and Publications

August 2017Income and Wealth Distribution in Macroeconomics: A Continuous-Time Approach
with Yves Achdou, Jiequn Han, Jean-Michel Lasry, Benjamin Moll: w23732
We recast the Aiyagari-Bewley-Huggett model of income and wealth distribution in continuous time. This workhorse model – as well as heterogeneous agent models more generally – then boils down to a system of partial differential equations, a fact we take advantage of to make two types of contributions. First, a number of new theoretical results: (i) an analytic characterization of the consumption and saving behavior of the poor, particularly their marginal propensities to consume; (ii) a closed-form solution for the wealth distribution in a special case with two income types; (iii) a proof that there is a unique stationary equilibrium if the intertemporal elasticity of substitution is weakly greater than one; (iv) characterization of “soft” borrowing constraints. Second, we develop a simple...
July 2015The Dynamics of Inequality
with Xavier Gabaix, Jean-Michel Lasry, Benjamin Moll: w21363
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 tails of the income and wealth distributions at a given point in time, 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 an order of magnitude too slow relative to those observed in the data. We then suggest parsimonious deviations from the basic model that can explain such changes, namely heterogeneity in mean growth rates or deviations from Gibrat's law. These deviations are consistent with theories in which the increase in top income inequality is driven by the rise of "superstar" entreprene...

Published: Xavier Gabaix & Jean‐Michel Lasry & Pierre‐Louis Lions & Benjamin Moll, 2016. "The Dynamics of Inequality," Econometrica, Econometric Society, vol. 84, pages 2071-2111, November. citation courtesy of

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