Comment by 0xcde4c3db

Not a lawyer (let alone one specializing in antitrust law), but it looks like the relevant legal standard is "dominant position". Basically, it's legal to have a dominant position, but that position can be abused through certain categories of actions. By contrast, under the Sherman Act it's nominally a felony to even attempt to become a monopoly (although the application of this by courts has apparently been both complex and contentious).