Market structure refers to the key characteristics of an industry that determine the nature and intensity of competition and pricing behaviour of firms within it.
## Core concept
Market structure is determined by: - Number and size of firms — how many sellers and their relative market share - Nature of product — homogeneous (identical) vs differentiated - Barriers to entry and exit — ease with which new firms can join or leave - Price-setting power — whether firms are price-takers or price-makers - Information availability — transparency of prices, quality, costs
These characteristics create a spectrum from perfect competition (most competitive) to monopoly (least competitive), with monopolistic competition and oligopoly occupying the middle ground.
## Four main market structures
### Perfect Competition - Very large number of small firms, each with negligible market share - Homogeneous (identical) products - No barriers to entry/exit - Firms are price-takers — accept the market price set by supply and demand - Perfect information; no need for advertising - *Example:* Agricultural markets, forex trading
### Monopoly - Single firm dominates the entire market - Unique product with no close substitutes - High barriers to entry (patent, licence, natural monopoly, economies of scale) - Firm is price-maker — sets price subject to demand curve - May restrict output and charge higher prices - *Example:* Utilities (water/electricity), branded pharmaceuticals under patent
### Monopolistic Competition - Many firms but with differentiated products - Each firm has some price-setting power over its variant - Low to moderate barriers to entry - Heavy use of branding, advertising, packaging to differentiate - Short-run supernormal profits possible; eroded in long run by competition - *Example:* Fast food chains, cosmetics, ready-made garments
### Oligopoly - Few large firms dominating the market - Products may be homogeneous (steel, cement) or differentiated (automobiles, phones) - High barriers to entry (capital, technology, brand loyalty) - Firms are interdependent — decisions of one firm affect others, leading to strategic behaviour - Price rigidity common; firms avoid price wars; use non-price competition - *Example:* Automobiles, airlines, telecom operators, cement manufacturers
## Comparison framework (for exam answers)
| Aspect | Perfect Competition | Monopolistic Competition | Oligopoly | Monopoly | |--------|-------------------|-------------------------|-----------|----------| | Number of firms | Very many | Many | Few | One | | Product nature | Homogeneous | Differentiated | Homo/Differentiated | Unique | | Entry barriers | None | Low | High | Very high | | Price control | None (price-taker) | Some (limited) | Significant (interdependent) | Complete (price-maker) | | Advertising | None | Extensive | Moderate to high | Limited | | Long-run profit | Normal | Normal | Supernormal possible | Supernormal |
## Common exam applications
- Identify market structure from given industry characteristics
- Predict firm behaviour — pricing, output, advertising decisions
- Explain barriers to entry and their effect on competition
- Distinguish between firms' strategies in different structures (e.g., why oligopolists avoid price wars)
- Link to welfare — perfect competition maximises consumer surplus; monopoly restricts output
## Common mistakes
- Confusing monopolistic competition with oligopoly (remember: mono-competition = many firms with differentiated products; oligopoly = few firms)
- Assuming all monopolies are harmful (natural monopolies may be efficient due to economies of scale)
- Ignoring interdependence as a defining feature of oligopoly
- Treating "few firms" and "oligopoly" as synonymous without checking product differentiation and entry barriers
Exam tip: Structure answers using the framework above. Start by identifying the number of firms, then product nature, barriers, and price-setting power to classify the structure accurately.