Contestable market
In economics, the theory of contestable markets, associated primarily with its 1982 proponent William J. Baumol, held that there are markets served by a small number of firms that are nevertheless characterized by competitive equilibrium, and therefore desirable welfare outcomes, because of the existence of potential short-term entrants. == Theory == A perfectly contestable market has three main features: No entry or exit barriers No sunk costs The same level of technology is available to incumbent businesses and new entrants.