@OP
There have been (and are) a few corporate monopolies in America. Until 1984 for example, AT&T had a monopoly on American phone service (BT had a similar arrangement in the UK, most countries did). You didn't even own your own telephone; you had to lease it for a few dollars a month. In many states/areas also the utilities are monopolies: you buy electricity from the local monopoly power company or you're off the grid.
The way it worked was in exchange for a legally sanctioned and protected monopoly, the phone/utility company agreed to regulation of prices and profit. AT&T traded their monopoly in 1984 for a chance to break into the computer market (which failed) and they were split into regional companies (Verizon, SBC, Pacific Bell, USWest, etc) which are beginning to clump back together again. It's an interesting story and I recommend the Wikipedia article about the Bell System.
Now to your question: one company owning everything would be the same as totalitarian communism (like in the old USSR or North Korea) and would probably have the same result.
(Edited 56 seconds later.)
@previous (Metæ)
1984 is here! It's here, today! Ma Bell never died!