America's Superstar Companies Are a Drag on Growth

Here’s a story about the U.S. economy that more people are telling these days. Since the 1980s, antitrust enforcement has gotten weaker. As a result, a few big companies have managed to capture a much bigger share of the market in various industries. Technology may have helped too, by letting big companies spread their geographic reach, and by creating network effects that keep customers locked in to platforms like Facebook. Anyway, as a result of this increased market power, the big superstar companies have been raising their prices and cutting their wages. This has lifted profits and boosted the stock market, but it has also held down real wages, diverted more of the nation’s income to business owners, and increased inequality. It has also held back productivity, since raising prices restricts economic output.

Like all big, sweeping theses about the economy, this story can’t be proven or disproven with a single research paper, or even a dozen papers. But like detectives, economists can probe various pieces and see how each one checks out. In the past few years, researchers have found that industrial concentration -- measured by the market share of the four biggest companies in an industry -- has indeed been increasing in most parts of the U.S. economy. They’ve documented a correlation between industrial concentration and a decline in labor’s share of national income. They’ve confirmed that profits have risen substantially. They’ve documented a slackening in the enforcement of antitrust law. And they’ve found some evidence that after mergers, prices go up while productivity doesn’t improve.