The Obama Administration's Council of Economic Advisers expressed concern that competition was threatened by increasing industry concentration. Academics, commentators, and journalists have joined the chorus. But none demonstrated increasing concentration of meaningful markets, as are used in...

Recent claims of increasing economic concentration have helped make competition policy a political issue, but the cited evidence does not point to an upward trend in concentration at the market level—the level at which competition occurs. The modest upward trends in concentration observed for...