Market Structures in Economics: Concentration, Entry Barriers and Market Power

Market Structures in Economics

Market structure refers to the number and size distribution of buyers and sellers in a market, the degree of product differentiation, and the ease with which firms can enter or leave the market.

Market Concentration

The number and size of firms in a market determine its concentration. The concentration ratio (CR) measures the share of total sales held by the largest firms. For example, CR3 or CR4 represents the combined market share of the three or four largest companies. High concentration suggests market power, while dispersed companies suggest a more competitive market.

Barriers to Entry

Barriers to entry are factors that make it easier or harder for new companies to enter and leave a market. Low barriers allow free movement in and out of the market, while high barriers protect existing firms.

Product Homogeneity

Homogeneity refers to whether products are identical or whether substitute products exist. In a market with homogeneous products, all goods are equal in the eyes of consumers.

Types of Market Structures

1. Perfect Competition

• Concentration: Many companies offer identical products and each is a price taker; market price is determined by supply and demand.
• Barriers to entry: Free entry and exit, so firms earn only normal profits in the long run.
• Homogeneity: Products are perfect substitutes.
• Efficiency: Production occurs at minimum average total cost, and inefficient firms are eliminated.

Monopolistic competition is similar to perfect competition, except that products are differentiated and firms face a downward-sloping demand curve.

2. Oligopoly

• Concentration: A few large companies dominate the market. Their decisions depend on the competitors' reactions. There is a tendency to reach agreements, such as cartels or collusion, which can bring prices closer to monopoly or perfect competition levels.
• Homogeneity: Products may be homogeneous or differentiated. Price wars can lead to prices close to perfect competition levels, while cartels bring prices closer to monopoly levels.
• Types:
  • Cartel: Firms agree on prices or production levels and divide the market.
  • Independent demand: No firm's decisions significantly influence the demand of others.
  • Price leader: A dominant firm sets the price, and others follow its guidelines. Dumping occurs when a firm sells below cost.
  • Kinked demand: If a firm lowers its price, competitors will also lower theirs, so demand becomes inelastic in that range.
• Barriers to entry: High, due to economies of scale, large investments, and strategic practices such as heavy advertising, technological innovation, and excess production capacity that deter new entrants.

3. Monopoly

• Concentration: A single company is the only seller. It acts as a price setter and determines price or quantity. Its market share is 100%.
• Barriers to entry: Very high.
  • Natural: Economies of scale make it efficient for one firm to supply the whole market.
  • Legal: The state grants a single company the right to produce or provide a service.
  • Technological: The company controls a key factor of production or raw material.
• Price discrimination:
  • First degree: Each consumer pays the maximum they are willing to pay.
  • Second degree: Prices vary by quality or quantity purchased.
  • Third degree: Different groups of consumers are charged different fixed prices.
• Mergers: Firms can combine to strengthen their market position.

Market Failures

Externalities

An externality occurs when an economic agent is affected by the actions of another without compensation. It creates a difference between the private cost and the social cost of an activity. Externalities can be positive or negative.

• Solutions to internalize the problem:
  • Direct control: Establishing rules, regulations, permits, inspections, and fines.
  • Indirect control: Taxes, subsidies, and tradable pollution permits that give incentives to take social costs into account.

Public Goods

Public goods have two main characteristics:

• No rivalry: One person's consumption does not reduce the amount available to others.
• Non-excludability: No one can be prevented from consuming the good, even if they do not pay.

Common Resources

Common resources are non-excludable but rival. Because no one can be excluded from using them, they may be overused and depleted.

Merit Goods

Merit goods are goods that are considered socially desirable, so they are provided or promoted even if not all consumers would choose to buy them or would buy them in sufficient quantity.