Over the past three decades, the U.S. government has permitted corporate giants to take over an ever-increasing share of the economy. Monopoly—the ultimate enemy of free-market competition—now pervades every corner of American life: every transaction we make, every product we consume, every news story we read, every piece of data we download. Eighty percent of seats on airplanes are sold by just four airlines. CVS and Walgreens have a virtual lock on the drugstore and pharmacy business. A private equity firm in Brazil controls roughly half of the U.S. beer market. The chemical giant Monsanto is able to dictate when and how farmers plant its seeds.... According to a study published earlier this year, half of all publicly traded companies have disappeared over the past four decades &Google and Facebook control nearly 75 percent of the $73 billion market in digital advertising.