The Secretive Industry Devouring the U.S. Economy

The publicly traded company is disappearing. In 1996, about 8,000 firms were listed in the U.S. stock market. Since then, the national economy has grown by nearly $20 trillion. The population has increased by 70 million people. And yet, today, the number of American public companies stands at fewer than 4,000. How can that be?

One answer is that the private-equity industry is devouring them. When a private-equity fund buys a publicly traded company, it takes the company private—hence the name. (If the company has not yet gone public, the...