Google, Microsoft and the threat from overmighty trustbusters

There are mergers to worry about and mergers to welcome. In the first category are tie-ups between biggish firms in the same line of business. In these “horizontal” mergers, a competitor is taken out of the market, removing a constraint on prices. In such cases, competition authorities will investigate the merger and may block it. Other mergers have historically been considered less troublesome. If a firm buys another in an adjacent line of business (a conglomerate merger) or if a supplier buys a customer (a vertical merger), the effects on competition have been seen as benign.