Contestability concerns the threat of entry and exit, not simply the number of incumbent firms.
Must know
- Low barriers make potential competition credible.
- Sunk costs discourage exit and entry.
- Incumbents may limit prices to deter entry.
Must know definitions
Contestable market: a market with no significant barriers to entry or exit, where the threat of potential competition disciplines incumbent firms even if actual competition is limited.
Hit-and-run entry: a new firm entering a market to take advantage of supernormal profit, then exiting once that opportunity disappears.
Limit pricing: setting price below the profit-maximising level, but low enough to deter entry by making it unprofitable for a new firm to compete.
Sunk costs: costs already incurred that cannot be recovered if a firm exits the market.
Explain and apply
Mechanism in brief: If entry is feasible and exit losses are small, high incumbent profits attract entrants. The credible threat can constrain price even before entry actually occurs.
Distinguish: Low fixed costs and low sunk costs are different; concentration alone does not measure contestability.
Use the extract: Look for sunk costs, access to networks and the credibility of entry, rather than counting incumbent firms alone.
Characteristics of contestable markets
A contestable market is one with no barriers to entry or exit, no sunk costs (start-up costs that cannot be recovered on exit), new firms facing no competitive disadvantage compared to incumbents, and equal access to the same technology as existing firms.
- In the model of a perfectly contestable market, incumbents cannot sustain price above average cost: supernormal profit attracts hit-and-run entry that competes it away. A highly contestable market may face strong entry pressure without meeting all the assumptions of perfect contestability.
no barriers to entry/exit + no sunk costs + equal access to technology → threat of entry is credible → incumbents constrained to price close to AC even without actual new entrants
Implications of contestable markets for the behaviour of firms
If an incumbent earns supernormal profit, it becomes vulnerable to hit-and-run entry: a new firm enters, takes a share of the supernormal profit, and exits again once conditions change, without needing to stay long-term.
- To avoid this, incumbents in a highly contestable market tend to price where P = AC, leaving no supernormal profit and therefore no incentive for entry, or set a limit price — a price below the profit-maximising level but low enough to deter new entrants.
- This means the mere threat of potential competition can discipline firm behaviour just as much as the presence of actual rivals, and a highly contestable market can behave much like a perfectly competitive one even with only a few firms actually operating in it.
threat of hit-and-run entry → incumbent prices at P=AC or sets a limit price → no supernormal profit available to attract entrants → incumbent behaves competitively despite few actual rivals
Costs and benefits of contestability for firms and consumers
| Stakeholder | Costs | Benefits |
|---|---|---|
| Firms | Harder to earn or sustain supernormal profit; constant pressure to keep costs and prices low | Access to markets is easier, opening opportunities to enter profitable industries when conditions are favourable |
| Consumers | — | Lower prices and more choice than in a market with low contestability |
The significance of sunk costs for contestability
Sunk costs are costs that cannot be recovered once spent, such as advertising or specialised equipment with no resale value.
- High sunk costs make both entry and exit less attractive, since a firm that enters and later needs to leave cannot recoup these costs — this discourages hit-and-run entry and reduces contestability.
- Markets with high sunk costs therefore tend to have pricing and output behaviour closer to a monopoly than to a perfectly competitive market, since incumbents face less credible threat of entry.
sunk costs ↑ → cost of failed entry/exit ↑ → hit-and-run entry becomes less attractive → contestability ↓ → incumbent pricing behaviour shifts towards the monopoly outcome
Efficiency assessment
| Efficiency type | Achieved? | Reasoning |
|---|---|---|
| Allocative efficiency | Not guaranteed | Entry threats can push price towards average cost, but this does not ensure P = MC, especially with economies of scale. |
| Productive efficiency | Not guaranteed | Entry threats encourage cost control, but operation at minimum average cost also depends on demand and the scale of production. |
| Dynamic efficiency | Limited | Constrained profit under high contestability leaves less retained profit to fund R&D, though firms may still innovate to build a cost or differentiation advantage that deters entry |
| Economies of scale | Depends | Not guaranteed by contestability itself — depends on the underlying cost structure of the industry, which is independent of how contestable it is |
Impact on stakeholders
| Stakeholder | Pros | Cons |
|---|---|---|
| Consumers | Lower prices and more choice than under low contestability; closer to allocative and productive efficiency | — |
| Producers | Easier access to enter profitable markets and capture some supernormal profit before competition arrives | Persistent pressure limits the ability to sustain supernormal profit; harder to fund long-run investment |
| Government | Promoting contestability (e.g. deregulation, removing barriers) is a lower-intervention way to discipline firm behaviour than direct price regulation | Must still monitor markets, since true perfect contestability rarely exists in practice |
| Society | Encourages efficient resource allocation without needing constant regulatory intervention | High sunk-cost industries remain resistant to contestability, limiting how widely these benefits can be achieved |
Brand loyalty, network access and retaliation can make entry less credible despite low formal barriers. Judge practical entry conditions and recoverable costs rather than using the number of incumbents as a proxy.
Rapid recap
Contestability concerns credible potential entry and exit. Sunk costs are unrecoverable; fixed costs need not be sunk. Few firms can face strong potential competition.
Diagram cue: use the firm diagram only if it clarifies entry incentives.
Related chapters: Unit 3 chapter 11 (p. 50) · Unit 3 chapter 19 (p. 88)