Concentration-based screens for horizontal mergers, such as those employed in the US DOJ and FTC Horizontal Merger Guidelines, play a central role in merger analysis. However, the basis for these screens, in both form and level, remains unclear. We show that there is both a theoretical and an...

The heavy-tailed distribution of firm sizes first discovered by Zipf (1949) is one of the best established empirical facts in economics. We show that it has strong implications for asset pricing. Due to the concentration of the market portfolio when the distribution of the capitalization of...

We propose an economic model of business groups that allows for the cooperative behavior of groups of firms, where the number and size of each group is determined endogenously. In this framework, more than one configuration of groups can arise in equilibrium: several different types of business...

In this paper, we provide a conceptual framework for understanding the phenomenon of exclusive dealing, and we explore the motivations for and effects of its use. For a broad class of models, we characterize the outcome of a contracting game in which manufacturers may employ exclusive dealing...

In the context of a model that distinguishes between large money center banks and smaller regional banks, we show that the percentage of a country's debt held by the large banks affects the secondary market price of that country's debt: the higher the concentration of the debt, the higher the...

The fall of labor's share of GDP in the United States and many other countries in recent decades is well documented but its causes remain uncertain. Existing empirical assessments of trends in labor's share typically have relied on industry or macro data, obscuring heterogeneity among firms. In...

The recent fall of labor's share of GDP in numerous countries is well-documented, but its causes are poorly understood. We sketch a "superstar firm" model where industries are increasingly characterized by "winner take most" competition, leading a small number of highly profitable (and low labor...

This paper explores how different margins of market share are related to markups. Using merged microdata on producers and consumers, we document that a firm's market share is mainly related to its number of customers, while its price-cost markup is associated only with its average sales per...