Perfectly Competitive Market
A perfectly competitive market is a theoretical market structure in which many small firms sell an identical product to many buyers, all participants have complete information, and there are no barriers to entry or exit. Firms in perfect competition are price takers: they must accept the market price determined by the interaction of market supply and demand.[1]
Assumptions
Perfect competition rests on a set of stringent assumptions:
| Assumption | Description |
|---|---|
| Many buyers and sellers | No single participant can influence the market price. |
| Homogeneous products | All firms sell identical goods. |
| Perfect information | All participants know prices and product characteristics. |
| Free entry and exit | Firms can enter or leave the market without cost. |
| Perfect factor mobility | Resources can move freely between uses. |
Short-run and long-run equilibrium
In the short run, a competitive firm maximises profit by producing where marginal cost equals price. If price exceeds average total cost, the firm earns an economic profit. In the long run, however, positive profits attract entry, which increases market supply, lowers price, and drives profit to zero. The long-run equilibrium is therefore characterised by normal profit only, with price equal to the minimum of long-run average cost.[1]
Efficiency
Perfect competition is used in economics as a benchmark of efficiency. In long-run equilibrium, the market achieves allocative efficiency (price equals marginal cost) and productive efficiency (production at minimum average cost). It also achieves Pareto efficiency, as formalised in the first fundamental theorem of welfare economics.[1]
Real-world relevance
Few, if any, real markets satisfy all the assumptions of perfect competition. The model is nonetheless important as an analytical benchmark against which other market structures—such as monopoly, oligopoly, and monopolistic competition—are compared.[1]