I set the bar even lower than the other commenter. I don't care if it's a monopoly, nor even really if it's engaged in anticompetitive practices. I just care if it's big, like big enough to have outsized market power. I think that markets with large disparities in size and market power among participants are inherently anticompetitive. I think that in most market sectors --- banks, automakers, airlines, media, you name it --- there are a small number of large companies with outsize market power, and those should all be broken up.