Is There a Monopoly?

In the seventies, an economist from harvard named sherer came up with a theory he called shared monopolies. He was their expert witness in a case against three companies who had differentiated their cereal. And yes, there's no reason to believe that they have a traditional monopoly, but these three companies have a high market share and therefore guilty as can be. But it is true that human beings differentiate a product for whatever reason. That's a good thing. Businesses are catering to their preferences. As consumers ate a consumer.