consolidation. The Commission did require Exxon and Mobil agreed to sell or sever supply contracts with 2,143 gas stations in the Northeast and mid-Atlantic states, California, and Texas, and to divest a large California refinery, oil terminals, a pipeline, and other assets. That represented one of the largest divestitures ever mandated by antitrust agencies. And FTC Chairman Robert Pitofsky warned that any further petroleum-industry mergers with similar "national reach" could come close to setting off "antitrust alarms." The FTC staff immediately recommended that the agency challenge a proposed purchase by BP Amoco PLC of Atlantic Richfield Company. Instead of merging, some firms have tried to bolster their business clout through joint ventures with competitors. Because these arrangements eliminate competition in the product areas in which companies agree to cooperate, they can pose the same threat to market disciplines that monopolies do. But federal antitrust agencies have given their blessings to some joint ventures they believe will yield benefits. Many American companies also have joined in cooperative research and development activities. Traditionally, companies conducted cooperative research mainly through trade organizations -- and only then to meet environmental and health regulations. But as American companies observed foreign manufacturers cooperating in product development and manufacturing, they concluded that they could not afford the time and money to do all the research themselves. Some major research consortiums include Semiconductor Research Corporation and Software Productivity Consortium. A spectacular example of cooperation among fierce competitors occurred in 1991 when International Business Machines, which was the world's largest computer company, agreed to work with Apple Computer, the pioneer of personal computers, to create a new computer software operating system that could be used by a variety of computers. A similar proposed software operating system arrangement between IBM and Microsoft had fallen apart in the mid-53