Markups and Inequality

We study the relationship between markups, firm concentration and inequality using a model of entrepreneurial dynamics in an environment with incomplete markets and borrowing constraints. A key ingredient of the model is that markups are endogenous so that the markup a producer charges depends on the amount of competition it faces. We ask two questions. First, what fraction of the rise in income and wealth inequality is due to changes in the U.S. tax code and decline in anti-trust enforcement that led to a rise in the level and dispersion of markups? Second, what are the consequences of policies aimed at curtailing the market power of firms and reducing the level of markups? We answer these questions by studying micro-level data on income and wealth, entrepreneurial activity and product market concentration through the lens of our model.