I think US anti-trust law has been far too toothless for far too long. I wish we had some politicians from the 1920-30's that would actually go after big companies instead of taking bribes. Did I say bribes? Sorry I meant campaign contributions.
I mean, I doubt you have any understanding of actual anti-trust cases. But by the time standard oil was broken up it was down to 60% market share and the price of oil continued to fall.
The only monopolies that have truly existed in the USA are government granted ones.