I was a business major, and we did have some discussions in Business Law and Legal Environment of Business about antitrust (US term) and competition law (European term). However, that was a _really_ long time ago.

For example, we talked a bit about one of the railroad barons (JP Morgan?) forcing a steel baron (Andrew Carnegie?) to sell by refusing to carry their products, and how no government intervention occurred.

We talked about Theodore Roosevelt as an early "trust-buster", and Franklin D Roosevelt as well.

It's all become very fuzzy in the intervening years.

However, if $COMPANY is large enough to set pricing and terms for the entire market, it has monopoly market power. That's just one measure of "too large".