No. The only requirement is a "dominant" player. https://www.ftc.gov/enforcement/anticompetitive-practices https://www.ftc.gov/enforcement/anticompetitive-pract

No. The only requirement is a "dominant" player. https://www.ftc.gov/enforcement/anticompetitive-practices https://www.ftc.gov/enforcement/anticompetitive-practices This is the reason why Microsoft and Google have both been investigated for anti-competitive behavior even though neither one of them was a monopoly. The Sherman Act prohibits using a dominant position in one area as leverage to exclude competitors in the same or different area. In other words, a dominant player has to play (more than) fair in any new markets. I say "more than" because if Amazon was not so dominate in ecommerce this behavior would be perfectly fine.