Duopoly

Companies operating in a duopoly face lower competition, because there are less rivals in the system. Lower competition means higher prices and better margins. Sometimes a duopoly can form from government intervention or through economies of scale. There are sometimes natural barriers, such has high capital expenditure costs that prohibit competitors from entering the system.

Source: http://en.wikipedia.org/wiki/Oligopoly

… "Duopoly" has a significant impact, so an analyst should put more weight into it.