How Do Oligopolies Affect Competition?

Recent news highlights a growing focus on government antitrust enforcement cases against companies accused of monopolizing markets and abusing their power. But let's consider another question: if a company lacks sufficient market power to qualify as a monopolist, but competes with only one or a handful of other companies, how does that affect consumer welfare?

American antitrust law seems to champion consumer choice untainted by anticompetitive practices. But it does not prohibit the market dynamic known as an oligopoly, which is a structure prevalent in numerous industries across the United States and the world. In an oligopoly, a small number of firms effectively control the quality, pricing, and supply of a particular market. This departure from perfect competition typically leads to some combination of higher prices and lower quality, and possibly less innovation and fewer consumer choices.