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...

Does the mere presence of big banks affect macroeconomic outcomes? In this paper, we develop a theory of granularity (Gabaix, 2011) for the banking sector, introducing Bertrand competition and heterogeneous banks charging variable markups. Using this framework, we show conditions under which...

We analyze private fixed investment in the U.S. over the past 30 years. We show that investment is weak relative to measures of profitability and valuation – particularly Tobin's Q, and that this weakness starts in the early 2000's. There are two broad categories of explanations: theories that...

Using patents as indicators of inventive activity, this article characterizes the concentration of origins of invention from 1976 to 2010, and how these changed over time. The analysis finds pervasive deconcentration in virtually every area related to ICT, but it can explain only a small part of...

We combine theory with data from different domains to provide an empirical analysis of the scale and variability of social capital as wealth. This is used to argue, given what we have learned in the literature on social capital, that the welfare returns to investing in trust could be...

Using a sample of Harvard undergraduates, we analyze trust and social capital in two experiments. Trusting behavior and trustworthiness rise with social connection; differences in race and nationality reduce the level of trustworthiness. Certain individuals appear to be persistently more...

Are individuals who trust others better off than those who do not? Do trustworthy people prosper more than untrustworthy ones? We first pose these questions in a search model where individuals face repeated choices between trusting (initiating an investment transaction) and not trusting, and...

Both individual experiences and community characteristics influence how much people trust each other. Using data drawn from US localities we find that the strongest factors that reduce trust are: i) a recent history of traumatic experiences, even though the passage of time reduces this effect...

We study the importance of discretion in antitrust enforcement by analyzing the response of asset prices to the sudden accession of Theodore Roosevelt to the presidency. During McKinley's term in office the largest wave of merger activity in American history occurred, and his administration did...