Correct. "Huge" in the case of antitrust matters is big enough to act anti-competitively. It's much more broad than you think, and it sees a lion share of litigation done by the Feds.
For example, there's currently an ongoing anti trust case against "Al’s Asphalt Paving Company"
> "Huge" in the case of antitrust matters is big enough to act anti-competitively.
With the extra clarification that just the size of the company or its market share aren't in and of themselves enough to constitute a crime. It's how the company acts once it has that power that constitutes the crime.
You could be a huge company, or dominate a market and still not run afoul of anti-competitive laws because you didn't abuse the position [0]. The abuse of position particularly (or only, depending on jurisdiction probably) if it brings harm to consumers is what lands a company in hot water.
For example, there's currently an ongoing anti trust case against "Al’s Asphalt Paving Company"
https://www.justice.gov/atr/case/us-v-als-asphalt-paving-com...