Since the inception of Medicare Part D in 2006, mergers and acquisitions (M&A) and regulatory changes have led to increased concentration and reduced plan variety in the standalone prescription drug plan (PDP) portion of the market. We examine how this industry consolidation affects Medicare...

We study the evolution of profits, investment and market shares in US industries over the past 40 years. During the 1990's, and at low levels of initial concentration, we find evidence of efficient concentration driven by tougher price competition, intangible investment, and increasing...

Do low interest rates contribute to the rise in market concentration? Using data on firm financials and high frequency monetary policy shocks, we find that falling interest rates disproportionately benefit industry leaders, especially when the initial interest rate is already low. Falling rates...

We examine whether and to what extent consolidation in the U.S. health insurance industry is leading to higher employer-sponsored insurance premiums. We make use of a proprietary, panel dataset of employer-sponsored healthplans enrolling over 10 million Americans annually between 1998 and 2006...

Economists have argued that a high concentration of land holdings in a country can create powerful interest groups that retard the creation of economic institutions, and thus hold back economic development. Could these arguments apply beyond underdeveloped countries with backward political...

For the first four decades of its existence the U.S. nuclear power industry was run by regulated utilities, with most companies owning only one or two reactors. Beginning in the late 1990s electricity markets in many states were deregulated and almost half of the nation's 103 reactors were sold...

This paper uses new data to reexamine trends in concentration in U.S. markets from 1994 to 2019. The paper's main contribution is to construct concentration measures that reflect narrowly defined consumption-based product markets, as would be defined in an antitrust setting, while accounting for...

We present estimates of 4 and 8 firm concentration ratios by industry and in weighted aggregate form for the manufacturing sector for Chinese enterprises for 2002 and 2007. These are then compared to available estimates for the same years and industrial classification for the US. These...

Studies of corporate governance are concerned with two features of modern shareholding: diffuse ownership and the resulting separation of ownership and control, which potentially leads to managerial self-dealing; and, majority shareholding, which potentially mitigates some managerial...