Contestable Market
What is Contestable Market?
A contestable market is one where entry and exit are cheap, so the threat of new firms holds price near cost even when only one or two sellers are active.
Contestability shifts the focus from how many firms are in a market to how easily another firm could arrive. A market is perfectly contestable when an entrant faces no sunk costs, can use the same technology, and can leave without loss, which makes hit-and-run entry possible: undercut the incumbent, take the profit, and exit before the incumbent can respond. Under those conditions even a single firm has to price near average total cost, because any economic profit invites a newcomer. What kills contestability is sunk cost, meaning spending that cannot be recovered on exit, such as advertising or a custom-built plant. This is why contestability is not the same as perfect competition: perfect competition needs many actual sellers, while a contestable market can have very few and still behave competitively.
Contestable Market: a worked example
Airline routes are the standard case, because the main asset can be flown somewhere else. Suppose one carrier serves a city pair where the average cost of a seat is $150 and it charges $250. A rival can lease an aircraft, sell seats at $180, clear $30 a seat, and on a 150-seat plane make $4,500 per flight, then redeploy the aircraft if the incumbent fights back. Knowing that, the incumbent holds its fare near $160 even though it is the only airline on the route. The plane, not the route, is the asset, so almost nothing is sunk.
The mistake students make with contestable market
Students assume a market with one or two sellers must be uncompetitive, and they treat high fixed costs as proof that entry is blocked. What matters is whether the costs are sunk, not whether they are large. A firm that spends heavily on aircraft or trucks it can resell later is still easy to enter against; a firm whose spending goes into non-recoverable advertising or a specialized plant is not.
Contestable Market questions
What makes a market contestable?
A market is contestable when new firms can enter and leave without sunk costs, using the same technology and facing the same buyers as the incumbent. Under those conditions the incumbent has to price as if rivals were already present, because any economic profit would attract hit-and-run entry.
Are contestable markets efficient?
A perfectly contestable market drives economic profit to zero and pulls price down to average total cost even with a single firm present, which delivers the productive efficiency result. It does not guarantee allocative efficiency, because where average cost is still falling, the price that just covers cost still sits above marginal cost.
Why do sunk costs reduce contestability?
Sunk costs reduce contestability because an entrant that cannot recover its spending stands to lose it outright if the incumbent responds with a price cut. That risk means the newcomer needs a large expected profit before entry is worth attempting, so the incumbent can charge above cost without drawing anyone in.
Formula / Example
This is the live Monopoly sandbox. Drag the curves, or open the full version.
Related terms
Common comparisons
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