Duopoly

As a duopoly or a duopoly market structure is referred to, in a variety of buyers, only two providers are facing. The duopoly is thus a special case of oligopoly. Due to its low complexity, the acceptance of a duopoly is often the subject of micro-economic theories.

Duopoly models

The two basic models are used in the consideration of oligopoly are:

• Quantity competition: Cournot oligopoly ( after Antoine -Augustin Cournot ), which shows that the two providers respond to changes in the production of each other with the quantity offered until a Nash equilibrium is reached.
• Price competition: model of Bertrand competition (after Joseph Bertrand ), the game-theoretic reasoning that underlies both providers act strategically about the prices.

Regarding the intensity of competition can be made about the prevailing degree of competitive interaction in duopoly no clear statement. Duopolmärkte can be characterized by strong competition to threaten the existence of price wars ( for example, in the case of chip makers Intel and AMD in the market for microprocessors). On the other hand, it may happen that important competitive mechanisms are circumvented by collusion of the seller.

Duopolies in politics

In the new political economy, the duopoly plays an important role as the political landscape of many countries is characterized by a duopoly. Typical examples are the United States, where there is only with the Republicans and the Democrats two relevant political parties. Some of the game-theoretic concept of the duopoly is also applied to the two German political parties SPD and CDU and their behavior.

Duopolies in the economy

True duopolies are rarely found in practice. Examples are:

• The mobile market in Germany than with T -D1 (now T-Mobile) and Mannesmann D2 (now Vodafone D2 ) announced the beginning of the 1990s, only two mobile operators on the German market.
• The duopoly for widebody aircraft - Airbus and Boeing are the only provider - is the world's largest and most famous duopoly.

More often exist - analogous to the quasi- monopolies - markets with quasi- duopolies:

• For credit card systems, there is a Europe-wide quasi- duopoly of the two providers MasterCard and VISA International Service Association.
• In the PC market, Intel and AMD form at the main processors and NVIDIA and ATI / AMD graphics cards in the quasi- duopolies.
• Quasi - duopolies are also the two Swiss retailer Migros and Coop ( Switzerland ), as well as Autoscout24 and Mobile.de at the online car markets.