The answer is "Oligopoly".
Oligopoly is a market structure with few firms, none of which can shield the others from having huge impact. The focus proportion estimates the piece of the overall industry of the biggest firms. An imposing business model is one firm, duopoly is two firms and oligopoly is at least two firms. There is no exact maximum breaking point to the quantity of firms in an oligopoly, however the number must be low enough that the activities of one firm altogether impact the others.
