Market Structures: Perfect Competition, Monopoly, Monopolistic Competition and Oligopoly Features for SSC CGL Economics

A market structure describes how a market is organised: how many firms there are, how similar their products are and how easy it is to enter. This is a standard topic in SSC CGL Finance and Economics. This guide on market structures for SSC compares perfect competition, monopoly, monopolistic competition and oligopoly in tables, with examples, price discrimination, the Competition Act and practice questions.

Comparison of Market Structures

Perfect Competition

• Many buyers and sellers, so that no single firm can influence the price; the firm is a price taker.
• Perfect knowledge and perfect mobility of factors.
• Price = AR = MR, and the firm’s demand curve is horizontal.
• Equilibrium is at MC = MR (= Price) with MC rising.
• In the short run a firm may earn super-normal profit or loss; in the long run all firms earn only normal profit.

Monopoly

• There is only one seller of a product with no close substitutes.
• Barriers to entry are legal (patents, licences), natural (control over raw material) or economic (huge capital).
• The monopolist is a price maker, and the AR curve is downward sloping with MR below it.
• Equilibrium is at MC = MR, and the monopolist can earn super-normal profit even in the long run.
• A natural monopoly arises when one firm can supply the whole market at a lower cost (railways, water supply).
• Price discrimination: charging different prices to different buyers for the same product (student discounts, electricity rates).

Degrees of Price Discrimination

Monopolistic Competition

This structure, developed by Edward Chamberlin, combines the features of competition and monopoly. Each firm has some control over its price because its product is differentiated by brand, quality or packaging, but there are many close substitutes. Firms spend a lot on advertising and sales promotion.

Oligopoly

• A few large firms dominate the market, and each firm’s decision depends on the reaction of its rivals (interdependence).
• The kinked demand curve model of Paul Sweezy explains why prices are rigid: rivals match a price cut but do not follow a price rise.
• A cartel is an agreement among firms to fix prices and output, such as OPEC in the oil market.
• Duopoly is an oligopoly with two sellers.
• Non-price competition such as advertising is common.

Other Market Forms

Regulation in India

The Competition Act, 2002 replaced the MRTP Act, 1969, and created the Competition Commission of India (CCI), which became fully functional in 2009, which prevents anti-competitive agreements, abuse of dominant position and harmful mergers.

Solved Examples

Example 1. In which market structure is price equal to marginal revenue?
Perfect competition.

Example 2. Which market structure has a kinked demand curve?
Oligopoly.

Example 3. Indian Railways in passenger transport is an example of which market?
Monopoly.

Quick Tips

• Learn the comparison table by heart.
• Remember the keywords: price taker, price maker, interdependence, differentiation.
• Remember that long-run profit is normal only in perfect competition.
• Know the Sweezy kinked demand curve for oligopoly.

Quick Revision Points

• Perfect competition: AR = MR = price; price taker.
• Monopoly: single seller; AR > MR; price maker.
• Monopolistic competition: differentiated products; advertising.
• Oligopoly: few sellers; kinked demand curve; cartel.
• Competition Act, 2002 and CCI regulate competition in India.

Practice Questions With Answers

1. In which market is the firm a price taker?
   Answer: Perfect competition
2. Which market has a single seller?
   Answer: Monopoly
3. Who developed the kinked demand curve model?
   Answer: Paul Sweezy
4. What is a cartel?
   Answer: An agreement among firms to fix price and output
5. What is a market with a single buyer called?
   Answer: Monopsony
6. Which market structure has differentiated products and many sellers?
   Answer: Monopolistic competition
7. Which Act replaced the MRTP Act in India?
   Answer: Competition Act, 2002
8. What profit does a firm earn in the long run in perfect competition?
   Answer: Normal profit
9. What is the AR curve of a firm in perfect competition?
   Answer: Horizontal (perfectly elastic)
10. Which organisation is an example of an international cartel?
    Answer: OPEC

How to Practise This Chapter

Practise 10 questions every day and write the steps on paper. Then attempt timed sets from our practice papers and the previous year papers page. See all topics on the Finance and Economics notes page, read the previous topic Production and Cost Theory and the next topic International Trade and Balance of Payments.

Frequently Asked Questions

What is perfect competition?

A market with a large number of buyers and sellers dealing in an identical product with free entry and exit.

What is a monopoly?

A market with a single seller and no close substitutes.

What is monopolistic competition?

A market with many sellers offering differentiated products.

What is oligopoly?

A market dominated by a few large sellers.

What is price discrimination?

Charging different prices from different buyers for the same product.

What is a natural monopoly?

A market where a single firm can supply the whole output at the lowest cost, such as railways.

What is the kinked demand curve?

A model that explains the price rigidity in oligopoly.

What is a cartel?

A group of firms that agree to control price and output.

What is monopsony?

A market with a single buyer.

What does the Competition Commission of India do?

It prevents anti-competitive practices in the market.

Is this topic asked in SSC CGL?

Yes, it is a regular topic in the Finance and Economics paper.

In which market is MR equal to AR?

In perfect competition.