Contestable Markets: The "Open Door" Theory

Welcome to one of the most interesting parts of Economics! Usually, when we think of competition, we look at how many shops are on a high street. But contestable market theory suggests that the actual number of firms doesn't matter as much as the threat of new firms joining in.

Don't worry if this sounds a bit backwards at first. By the end of these notes, you’ll understand why even a single massive company might behave like a friendly local business just because they are afraid of someone else "knocking on their door."

1. What is a Contestable Market?

A contestable market is a market where there is freedom of entry and exit. This means new firms can join the industry easily, and if they don't make money, they can leave without losing a fortune.

In a perfectly contestable market:

  • There are no barriers to entry (nothing stopping you from starting the business).
  • There are no barriers to exit (nothing stopping you from closing down).
  • Firms have access to the same technology.
  • There are no sunk costs.

The Core Idea: It’s the threat of competition that influences how a firm behaves. If a monopoly (a single seller) knows a rival could easily jump in and take their customers, they won't charge sky-high prices.

Analogy: Imagine a pop-up lemonade stand. If it’s easy to set up a table and sell lemonade, the person already selling it won't charge £10 a glass. If they did, you’d just put your own table next to theirs and sell it for £1!

Quick Review:

Contestability is about how easy it is to enter a market, not how many firms are already there.

2. The "Deal Breaker": Sunk Costs

This is the most important concept in this chapter. Sunk costs are costs that cannot be recovered when a firm leaves an industry.

Examples of Sunk Costs:
- Highly specialized machinery that can't be resold.
- Expensive advertising campaigns (you can't "un-buy" a TV ad).
- R&D (Research and Development) costs.

Why do they matter?
If sunk costs are high, the "exit" door is locked. If a firm knows it will lose millions just by trying to enter and failing, it simply won't enter. Therefore, for a market to be contestable, sunk costs must be low or zero.

Memory Aid: "Sunk Like a Stone"
Think of a stone thrown into the ocean. Once it's gone, you can't get it back. That’s a sunk cost. If you can get your money back (like selling a van you bought), it’s not a sunk cost!

Did you know? A delivery van is usually not a sunk cost because you can sell it to another business. However, painting that van with a permanent logo that costs £2,000 to remove is a sunk cost!

Key Takeaway: Low sunk costs make a market more contestable because they reduce the risk for new firms entering the market.

3. "Hit and Run" Competition

Because entry and exit are so easy in contestable markets, new firms can engage in what economists call hit and run entry.

How it works:
1. An existing firm starts making supernormal profits (high profits).
2. A new firm sees this, "hits" the market by entering quickly.
3. They "run" off with some of the profit.
4. They "run" out of the market as soon as prices or profits start to fall.

This is only possible because there are no significant entry or exit costs to slow them down.

4. How Contestability Affects Firm Behavior

In your syllabus (Section 1.2), you learned about productive and allocative efficiency. Contestability forces firms to move toward these efficiencies.

If a market is highly contestable, existing firms will:
- Lower their prices: To make the market look less attractive to "hit and run" invaders. This is called limit pricing.
- Increase efficiency: They must keep their Average Costs (AC) as low as possible to stay competitive.
- Focus on quality: To keep customers loyal so they don't switch to a new entrant.

Mathematical Note:
In a perfectly contestable market, firms will eventually charge a price where \(P = AC\) (Normal Profit). If they charge \(P > AC\) (Supernormal Profit), new firms will enter and take that profit away.

Common Mistake to Avoid:

Don't confuse a contestable market with perfect competition. Perfect competition requires thousands of tiny firms. A contestable market could have just one giant firm, as long as the possibility of entry exists.

5. Government Intervention and Contestability

The government (and the Competition and Markets Authority) loves contestability because it benefits consumers through lower prices and better choice. They try to increase contestability through supply-side policies (Section 3.3 of your syllabus):

  • Deregulation: Removing "red tape" and legal rules that make it hard for new firms to start up.
  • Tougher Laws against Anti-competitive Behavior: Stopping big firms from using "predatory pricing" (dropping prices so low they bankrupt small rivals).
  • Privatisation: Selling state-owned businesses to the private sector to encourage more players to enter the field.

Key Takeaway: Government policy often focuses on opening up markets rather than just breaking up big companies. If the door is open, the market will often "police itself."

Final Summary Check

Check your understanding:
1. Is it the number of firms or the ease of entry that defines contestability? (Answer: Ease of entry)
2. What do we call costs that cannot be recovered? (Answer: Sunk costs)
3. Why does contestability lead to lower prices? (Answer: To prevent "hit and run" entry from rivals)

Don't worry if the diagrams for this feel a bit empty—usually, you just show a firm moving from a high price (monopoly profit) down toward their Average Cost curve to show they are trying to keep rivals out!