I once heard an interview of the CEO of a pickle company on the radio. He was talking about how his company began supplying pickles to Wal Mart some years back, and eventually they found Wal Mart accounted for over 75% of their business. Then Wal Mart began pressuring them to reduce their wholesale price, and they had no choice but to comply or to suffer considerable financial damage and lay off most of their workers. They chose to lower the price, which incidentally made it impossible to do anything about the already low wages paid to the migrant workers who pick the pickles.