Economics Feed

"Trends in Competition in the United States: What Does the Evidence Show?*"

Carl Shapiro and Ali Yurukoglu:

We explain that the empirical evidence relating to concentration trends, markup trends, and the effects of mergers does not actually show a widespread decline in competition. Nor does it provide a basis for dramatic changes in antitrust policy. To the contrary, in many respects the evidence indicates that the changes observed in a number of industries are likely to reflect competition in action.

Related: C. Lanier Benkard, Ali Yurukoglu, and Anthony Lee Zhang

This paper measures concentration in narrowly defined product markets for a broad range of consumer goods and services in the U.S. from 1994 to 2019. We document two main empirical facts. First, concentration levels are high. 44.4% of the markets in our sample are “highly concentrated” as defined by U.S. regulators. Second, market concentration has been decreasing since 1994.


"The Less-Efficient Market Hypothesis"

By Clifford Asness, Managing and Founding Principal, AQR Capital Management. Forthcoming in the Journal of Portfolio Management (this draft  is free). Abstract:

Market efficiency is a central issue in asset pricing and investment management, but while the level of efficiency is often debated, changes in that level are relatively absent from the discussion. I argue that over the past 30+ years markets have become less informationally efficient in the relative pricing of common stocks, particularly over medium horizons. I offer three hypotheses for why this has occurred, arguing that technologies such as social media are likely the biggest culprit. Looking ahead, investors willing to take the other side of these inefficiencies should rationally be rewarded with higher expected returns, but also greater risks. I conclude with some ideas to make rational, diversifying strategies easier to stick with amid a less-efficient market.