Industrial concentration” refers to a structural characteristic of the business sector. It is the degree to which production in an industry—or in the economy as a whole—is dominated by a few large firms. Once assumed to be a symptom of “market failure,” concentration is, for the most part, seen nowadays as an indicator of superior economic performance. In the early 1970s, Yale Brozen, a key contributor to the new thinking, called the profession’s about-face on this issue “a revolution in economics.” Industrial concentration remains a matter of public policy concern even so.