The model of perfect competition is one of the most famous, most important, and most misunderstood concepts in economics. Rather than aiming to be a full-blown model of real-world competitive markets, the perfect competition model isolates the decentralized coordination mechanism inherent in all...

Theory predicts a positive relationship between market concentration and profitability in most scenarios. In empirical work, however, this relation is frequently not found or only a weak connection is observed. We compare the performance of concentration and market share variables, which are...

A rapidly growing literature has shown that market concentration among domestic firms has increased in the United States over the last three decades. Using confidential census data for the manufacturing sector, we show that typical measures of concentration, once adjusted for sales by foreign...