markedsmagt

Markedsmagt, or market power, is the ability of a firm or group of firms to influence prices, terms, or the availability of goods and services beyond competitive levels. It arises from a dominant position, barriers to entry, or control of essential assets, enabling higher prices or restricted output without losing all customers.

Economists measure markedsmagt with indicators such as the Lerner index (P−MC)/P and market concentration measures like the Herfindahl-Hirschman Index (HHI) or CR4. Persistent profit margins and the ability to raise prices without proportional losses in demand signal power. Market power is not identical to a legal monopoly; it can be temporary or contextual.

Sources of markedsmagt include economies of scale, product differentiation, switching costs, control of essential facilities, vertical integration, exclusive distribution, patents, and network effects. In digital markets, platforms can accumulate power through data advantages and two-sided networks.

Power can lead to higher prices, reduced output, and lower consumer welfare, potentially hindering innovation. Competition policy and antitrust enforcement aim to curb abuse and preserve contestability. Tools include merger controls, prohibiting anti-competitive practices, and price regulation in natural monopolies.

In recent decades, attention has focused on large digital platforms where data, scale, and network effects sustain dominant positions. Critics argue that measurement challenges complicate policy, while supporters contend that robust enforcement helps preserve competitive markets.