Monopolies have long been a fixture of American life. Since the 1980s, when Ronald Reagan’s free-market policies reshaped the economy, they have become especially persistent. Today, companies with outsize market shares—from Big Tech and large investment banks to retailers and food conglomerates—dominate the US economy. The doctrine incubated by Milton Friedman and others at the University of Chicago, which emphasizes economic efficiency and deregulation, continues to prevail. This laissez-faire approach, presented in Friedman and Anna J. Schwartz’s A Monetary History of the United States,