The US government has always realized that monopolies can come to be "naturally" (that is, through normal market forces) in an industry. The US government over

The US government has always realized that monopolies can come to be "naturally" (that is, through normal market forces) in an industry. The US government over goes after a monopolist when they attempt to enter or influence a different market by exploiting their monopoly. The US government didn't go against Standard Oil because they owned 90% of the refineries in the US, they went after Standard Oil because Standard Oil was using their 90% oil refinery market share to control the rail shipping industry. The US government didn't go against Microsoft because they owned 90% of the PC operating system market, they went after Microsoft because Microsoft was using their 90% operating system market to control the web browser market (along with some other sub-computer markets). Why isn't the US government going against Monsanto (for instance?) Because they aren't trying to gain control of another industry outside agriculture (or better lobbyists, take your pick).