In general, it’s not healthy to think that the world is being run by a small cabal of men hidden in smoke filled rooms. This sort of thinking leads to the wearing of tin-foil hats and needless paranoia: most of the dangerous political and economic behaviour that alters our world happens in plain sight.
This isn’t to say that cartels and collusions aren’t real, and when regulators do their jobs, such dealings can be caught. In South Africa, for instance, a major commercial food manufacturer has just been fined R195 million (US$25 million) for its role in fixing the price of bread at the time of the food price crisis in 2007-8.
I’ve not heard of a similar case being brought in the United States. Either US corporations are far more law abiding, or the Bush administration had no inclination to investigate large-scale corporate malfeasance. You decide.