Markedsformer

Markedsformer is a concept in economics that describes the structural organization of a market. It characterizes how many buyers and sellers participate, how differentiated the products are, and how easily new firms can enter or exit. The market form helps determine prices, output levels, and the potential for welfare gains or losses.

The main forms are: perfect competition, in which many firms sell homogeneous products and prices are determined by supply and demand; monopolistic competition, where many firms offer differentiated products and maintain some price power; oligopoly, where a small number of firms tightly influence prices and outputs, often with interdependent decisions; and monopoly, in which a single firm dominates, facing high barriers to entry and substantial price setting ability.

Market form influences efficiency and incentives. Perfect competition tends toward allocative and productive efficiency in the long run, while monopolies can cause deadweight losses and reduced consumer surplus. Oligopolies may exhibit strategic behavior, price rigidity, and fluctuating profits. Regulation, technology, and network effects can shift or blur market forms over time.

Economists analyze market form using concentration measures such as the Herfindahl-Hirschman Index (HHI) or concentration ratios, and by applying game theory to model strategic interactions. Policy makers study market form to assess competition, regulate prices, and consider entry barriers or antitrust actions.

In practice, most real-world markets are imperfect and dynamic, combining elements of several forms or evolving with regulation and technology. Examples include agricultural markets approaching competition, utilities often regulated monopolies, and digital platforms that resemble oligopolies with strong network effects.