From Barry C. Lynn’s “The Case for Breaking Up Wal-Mart” (Harper’s: 24 July 2006):
Popular notions of oligopoly and monopoly tend to focus on the danger that firms, having gained control over a marketplace, will then be able to dictate an unfairly high price, extracting a sort of tax from society as a whole. But what should concern us today even more is a mirror image of monopoly called “monopsony.” Monopsony arises when a firm captures the ability to dictate price to its suppliers, because the suppliers have no real choice other than to deal with that buyer. Not all oligopolists rely on the exercise of monopsony, but a large and growing contingent of today’s largest firms are built to do just that. The ultimate danger of monopsony is that it deprives the firms that actually manufacture products from obtaining an adequate return on their investment. In other words, the ultimate danger of monopsony is that, over time, it tends to destroy the machines and skills on which we all rely.
Examples of monopsony can be difficult to pin down, but we are in luck in that today we have one of the best illustrations of monopsony pricing power in economic history: Wal-Mart. There is little need to recount at any length the retailer’s power over America’s marketplace. For our purposes, a few facts will suffice — that one in every five retail sales in America is recorded at Wal-Mart’s cash registers; that the firm’s revenue nearly equals that of the next six retailers combined; that for many goods, Wal-Mart accounts for upward of 30 percent of U.S. sales, and plans to more than double its sales within the next five years.
… The problem is that Wal-Mart, like other monopsonists, does not participate in the market so much as use its power to micromanage the market, carefully coordinating the actions of thousands of firms from a position above the market.