Estimating market power is often complicated by the lack of reliable measures of marginal cost. Instead, policy-makers often rely on other summary statistics of the market, thought to be correlated with price cost margins---such as concentration ratios or the HHI. In many industries, these...

We examine the interplay between market structure and the form that commodity taxation should take in a general equilibrium model in which firms produce differentiated products and so are able to exert market power. Our analysis takes account of two important recent developments that affect...

We propose a general equilibrium economy with oligopolistic output markets in which two channels can cause a change in market power: (i) technology, via changes to productivity shocks and the cost of entry, (ii) market structure, via changes to the number of potential competitors. First, we...

Collective reputation implies an important externality. Among firms trading internationally, quality shocks about one firm's products could affect the demand of other firms from the same origin country. We study this issue in the context of a large-scale scandal that affected the Chinese dairy...

How does a firm's market power in existing products affect its incentives to innovate? We explore this fundamental question using granular project-level and firm-level data from the pharmaceutical industry, focusing on a particular mechanism through which incumbent firms maintain their market...

We construct measures of industry performance and welfare in the U.S. car and light truck market from 1980-2018. We estimate a differentiated products demand model for this market using product level data on market shares, prices, and product characteristics, and consumer level data on...

We study how inertia interacts with market power and adverse selection in managed competition health insurance markets. We use consumer-level data to estimate a model of the California ACA exchange, in which four firms dominate the market and risk adjustment is in place to manage selection. We...

Might firms' use of data create market power? To explore this hypothesis, we craft a model in which economies of scale in data induce a data-rich firm to invest in producing at a lower marginal cost and larger scale. However, the model uncovers much richer interactions between data, welfare and...