Comment by estearum

Generally you don't hold a market dominant position in any sector that anti-trust regulators care about at 15 employees?

Frankly this stuff is impossible to talk about in the abstract. The details of every individual case matters. If you're actually curious (instead of just playing a shell game), you can go look up the types of analysis that FTC does to evaluate market dominance and whether a given transaction will excessively consolidate a market.