The United States Antitrust Laws were made 100 years ago. And as you can probably guess, they've not been too effective in recent years. Here's how they can be.

To add onto the point at 1:37, not only does it focus on preventing monopolies, it also looks more at any anti-competition behavior done by the company rather than the actual size of it. This means that a company can grow much larger- while still not being a monopoly -by simply not doing things specifically to undermine their competitors beyond reason. That's why I speak of market share and income as ways to control size, since a company can just have lower prices or happenstance its way into a monopoly without doing anything that could be considered "anti-competition".