A case of office block

HOW do you define a market? If it is America's market for office products, that depends on whom you ask. According to Staples, an office-supplies superstore chain that has since last September pursued a $4 billion takeover of Office Depot, its bigger rival, office products are sold in a fragmented $185 billion market in which the merged firm would have a meagre 5-6% share. According to the Federal Trade Commission (FTC), which on March 10th voted to block the deal, the merged group would dominate a much narrower “office-supply superstores” market, pushing up prices for consumers. After Staples and Office Depot agreed to sell some stores to a rival two days later, the FTC seemed set to back down. But does its tough “niche-market” approach to trustbusting make sense anyway?