Should regulators block CVS from buying Aetna?

AMERICA has a competition problem. Market concentration has risen in more than three-quarters of industries since the late 1990s. Concentration has led to higher profits and higher returns for shareholders at the expense of consumers. Antitrust authorities have become more supine: between 1970 and 1999, regulators brought an average of 16 cases a year in order to prevent big firms from becoming even bigger; between 2000 and 2014, that number fell below three.