Revision: Microeconomic Theory >> Forms of Market Economics ISC (Commerce) Class 12 CISCE

An oligopoly is a market structure in which a small number of large firms dominate the industry. These firms sell similar or differentiated products, and each firm’s decisions (such as pricing or output) directly affect the others, making them interdependent.

The term ‘market’ refers to the whole region in which buyers and sellers are in close contact to effect the purchase and sale of a product.

In economics, the term market refers to the mechanism or arrangement by which buyers and sellers of a commodity are able to interact with each other for having economic exchange and are able to strike a deal about the price and the quantity to be bought and sold.

“A market is the set of all actual and potential buyers of a product.”, Phillip Kotler

“Market includes both place and region in which buyers and sellers are in free competition with one another.”, Pyle

“A market means a body of persons who are in intimate business relations and carry on extensive transactions in any commodity.”, Jevons

“A market is a centre in which forces leading to exchanges of title to a particular product operate and towards which and from which the actual goods tend to travel.”, Clark and Clark

According to Augustin Cournot, “Economists understand the term 'market', not any particular marketplace in which things are bought and sold, but the whole of any region in which buyers and sellers are in such close contact with one another that the prices of the same goods tend to equality easily and quickly.”

Monopsony refers to a situation in which there is a single buyer of a commodity and in which the entry into the market by other buyers is impossible.

Monopolistic competition is a market structure in which the number of firms is large, there is free entry and exit of firms, and the firms produce differentiated products.

Product differentiation refers to differentiating the products on the basis of brand, size, color, shape, etc.

According to Chamberlin, “A General class of product is differentiated if any sufficient basis exists for distinguishing the goods of one dealer from those of another. Such a basis may be real so long as it is of importance whatsoever to buyers and leads to a preference for any variety of the product over another”.

An oligopoly is a market structure in which there are only a few big sellers.

Perfect competition is a form of market in which there are a large number of buyers and sellers and a homogeneous product is sold at a uniform price.

When a firm is able to sell the same product or service to two different categories of consumers at different prices, then it is known as price discrimination. Generally, a Monopoly firm is able to practice price discrimination successfully.

The act of selling the same product at different prices to different buyers is known as price discrimination.

A monopoly is a market situation in which a single firm sells a commodity, and there is no close substitute for the commodity the monopolist sells.

• According to Mrs Joan Robinson, "Perfect competition prevails when the demand for the output of each producer is perfectly elastic."
• "Perfect competition is characterised by the presence of many firms. All of them sell identical products. The seller is the price taker." – Bilas
• "Perfect competition prevails when the demand for the output of each producer is perfectly elastic." – Mrs Joan Robinson
• "Perfect competition describes a market in which there is a complete absence of direct competition among economic groups." – Ferguson

• "A pure monopoly exists when there is only one producer in a market, there are no direct competitors." – Ferguson
• "Monopoly is a market situation in which there is a single seller, there is no close substitute for commodity it produces, there are barriers to entry." – Koutsoyiannis

"Monopolistic Competition is found in the industry where there is a large number of small sellers, selling differentiated but close substitute products." – J.S. Bain

• “Oligopoly is that situation in which a firm bases its market policy in part on the expected behaviour of a few close rivals.”
  — J. Stigler
• “An oligopoly is a market of only a few sellers, offering either homogeneous or differentiated products. There are so few sellers that they recognise their mutual dependence.” — P.C. Dooley

"When there are exactly two sellers in the market this is a special case of oligopoly called duopoly." – Cohen and Cyret.

Monopsony is a market structure in which a single buyer (monopsonist) purchases the entire supply of a particular product or factor service, faces many sellers, and the entry of other buyers is very difficult or impossible.

• In common language, a market is a place where buying and selling occur.
• In economics, a market is any arrangement that allows buyers and sellers to meet (physically or virtually), decide a price, and exchange a commodity or service.​
• A market can be local, national, or international.
• Essential elements of a market: commodity, buyers and sellers, area of operation, communication/contact, and price.​
• There are two main ways to define a market: geographical (place‑based) and functional (activity‑based).​
• Competition among buyers and sellers tends to produce one prevailing price for the same commodity at the same time within a market.​

• Market structure describes how a market is organised and how much price power firms have.
• There is a spectrum from perfect competition (many firms, no price power) to monopoly (one firm, high price power), with monopolistic competition and oligopoly in between.
• Perfect competition: many sellers, homogeneous product, perfect knowledge, free entry/exit, and firms are price‑takers.
• Monopoly: one seller, no close substitutes, restricted entry, high price power.
• Monopolistic competition: many sellers, differentiated products, and some price power within limits.

• Perfect competition is an ideal market where many buyers and sellers trade identical products, and no one can control price.
• Firms and buyers are price takers; the price is fixed by industry demand and supply.
• Pure competition needs 3 conditions (large numbers, homogeneous product, free entry/exit).
• Perfect competition needs 7 conditions (3 basic + perfect knowledge, factor mobility, no selling costs, no transport costs).
• The model is used as a benchmark to judge how efficient other markets are.

• Monopoly is a market structure with one seller, no close substitutes, and barriers to entry.
• Main features: single seller, no close substitutes, barriers to entry, price maker, firm = industry, and possible price discrimination.
• Types include private, public, legal, natural, simple, discriminating, and voluntary (cartel) monopolies.
• Under monopoly, AR is the market demand curve; MR lies below AR because price must fall to sell more.
• Equilibrium output is found where MC=MR; price is taken from the AR curve at that output and is usually above MC.
• Cost curves (FC, AFC, AVC, AC, MC) have the usual shapes, but MC is not the supply curve in a monopoly.
• Price discrimination allows a monopolist to charge different prices by person, place, time, or use.

• Sellers compete mainly through product features and branding, not by price alone.
• No single seller can dominate the market or set global prices.
• Customers benefit from choice but may pay more for features created through branding.

• Oligopoly: A market with a few dominant firms, high interdependence, and barriers to entry.
• Firms compete both by price and by non‑price methods (advertising, quality, branding).
• Price rigidity and non‑price competition are typical features of oligopolistic markets.

• A duopoly is a market with exactly two dominant firms and is a special type of oligopoly.
• The key feature of duopoly is strong interdependence: each firm’s decisions affect the other, and each anticipates the rival’s reaction.
• Products may be homogeneous or differentiated, but only two firms control most of the market.
• Each firm faces uncertainty and cannot rely on a single, stable demand curve because demand depends on the rival’s behaviour.
• Strategic moves and counter‑moves (like price changes and advertising) are common in duopolistic markets.

• A bilateral monopoly exists when there is one seller (monopolist) and one buyer (monopsonist) in a market.​
• Both parties have strong market power and conflicting interests: the seller wants a high price, and the buyer wants a low price.​
• There is conflict over both the price and quantity of the product or factor being traded.
• Price and output are indeterminate because economic theory alone cannot predict a unique equilibrium; the outcome depends on bargaining.​
• The final price and quantity depend on the relative bargaining power of the monopolist and monopsonist.​

• Monopsony: one buyer, many sellers; buyer has market power.
• Monopsonist: the single powerful buyer.
• Main features: single buyer, many sellers, specialised input, low mobility of suppliers, buyer is price-maker.
• Common in labour markets (single large employer in a region; government as large employer).
• Joan Robinson is closely linked with the analysis of monopsony and imperfect competition.

• Markets can be classified using different criteria: time, area, quantity, functions, legality, control, and transactions.
• Each type helps us understand how and where different products are bought or sold.

• Market size depends on product, transport, policy, and more.
• Durable, portable goods = big market.
• Perishable or hard-to-transport = small market.
• Government rules can expand or limit the market.

• The demand curve of a firm is the same as its average revenue curve.
• Perfect competition: horizontal demand curve; firm is a price taker; demand is perfectly elastic.
• Monopolistic competition: downward‑sloping but flatter demand curve; demand is more elastic due to many close substitutes.
• Monopoly: downward‑sloping and steeper demand curve; demand is less elastic because there are no close substitutes.
• Elasticity of the firm’s demand curve mainly depends on the availability of close substitutes and the degree of control over price.