3.4.7 - Contestability

What Contestability Means

Contestability is about potential competition, not just actual competition. A market may contain only one large firm, but if new entrants can get in quickly, use similar technology, and leave without heavy losses, the incumbent cannot safely behave like an unconstrained monopolist.

This is a textbook extreme rather than a common real-world outcome. Potential entrants need access to similar technology and cost conditions to incumbents; otherwise existing firms keep a built-in advantage. Low consumer loyalty also helps, because buyers must be willing to switch. The absence of collusion matters too, because coordinated incumbent behaviour can shut out newcomers even when formal barriers look low.

Threat of Entry and Firm Behaviour

When an incumbent earns supernormal profit, that profit acts like a signal to outside firms. If entry is easy and exit is cheap, entrants can move in, take some of the profit, and leave again if it disappears. This is why economists talk about hit-and-run competition.

This possibility changes behaviour even before entry actually happens. An incumbent may choose limit pricing, accepting lower short-run profit so that potential entrants judge the market too unattractive to enter. In practice the limit price sits close to the average cost a new entrant would face, so an entrant could not expect to cover its costs. In other words, the threat of entry can be almost as important as entry itself.

In the textbook model of a perfectly contestable market, long-run normal profit is the only sustainable outcome. If firms tried to keep supernormal profit for long, entry would occur and squeeze it away. If firms were making persistent losses, exit would occur instead, so long-run losses are just as hard to sustain.

If an incumbent were producing above the lowest possible average cost, a rival with the same technology could enter, undercut, and take market share. At the minimum point of the average cost curve, MC = AC. So if price is forced down to average cost by contestability, the model implies:

That gives productive efficiency because the firm is operating at minimum average cost, and allocative efficiency because price equals marginal cost. In reality, these outcomes are strongest in the model rather than in every real market, but the logic explains why contestability matters to performance.

Barriers to Entry

Contestability falls as barriers to entry rise. The higher the cost, risk, or difficulty of entering a market, the weaker the threat from potential competition.

Some barriers are structural or innocent, meaning they arise from the nature of the industry rather than deliberate behaviour by incumbents. Important examples include:

• Economies of scale and a large minimum efficient scale. If entrants must produce on a large scale to get low average cost, they face a major disadvantage when starting small.
• Capital requirements. Industries such as steel, semiconductors, or pharmaceuticals need huge upfront investment.
• Network effects. A product may become more valuable the more people already use it, which gives established firms a built-in advantage.
• Natural monopoly conditions. If one firm can serve the market more cheaply than several firms, entry is much harder to sustain.

Other barriers are strategic, meaning incumbents deliberately create or strengthen them. These include:

• Patents and copyrights, which legally protect products or processes (they are often classed as legal barriers too, because the state grants them).
• Advertising and branding, which build customer loyalty and make switching less likely.
• Anti-competitive practices, such as exclusive contracts or refusing to deal with retailers that stock rivals.
• Predatory pricing, where price is cut below cost, accepting short-run losses, to force out rivals or deter entrants.
• Limit pricing, where price is kept low enough to make entry unprofitable.

There are also legal barriers created or enforced by government, such as licences and permits, professional qualifications, regulatory compliance costs, or exclusive rights to operate.