The spectrum of market structures and market power

Detail

1. What decides a market structure

• A market structure is a way of grouping markets into types. Five things decide the type:
• Number and size of sellers and buyers. Are there many small firms, a few big ones, or just one?
• Nature of the product. It can be homogeneous (every seller's unit is the same, like one grade of wheat) or differentiated (each seller's product looks different, like soap brands).
• Ease of entry and exit. Can a new firm start, or an old firm close, without large costs or legal blocks?
• Information. Do buyers and sellers know all prices and qualities?

• Control over price. Can one firm change the market price by its own action?

• The first four features decide the fifth. More firms, a more similar product, easier entry and better information all mean each firm has less control over price.

2. The benchmark: perfect competition

• Class 12 (The Theory of the Firm under Perfect Competition) lists four features of perfect competition:
• a large number of buyers and sellers, so each one is too small to change the price;
• a homogeneous product, so buyers do not care which seller they buy from;
• free entry and exit, so profits above normal attract new firms until those profits disappear;

• perfect information, so every buyer knows the price every seller charges.

• Result: price-taking. A price taker is a firm that must accept the market price as given.

• If it charges even slightly more, every buyer goes to a rival. It sells nothing.

• It has no reason to charge less, because it can already sell all it wants at the market price.

• The price line. The firm's demand curve is a horizontal line at the market price p.

• AR = MR = p. Average revenue (AR) is revenue per unit. Marginal revenue (MR) is the extra revenue from one more unit.
• Worked example: p = ₹20. Selling 10 units gives ₹200. Selling 11 units gives ₹220. MR = ₹20 = AR = p.
• Demand is perfectly elastic: elasticity is infinite, so a tiny price rise makes quantity sold fall to zero.

3. Price makers and the MR < AR rule

• A price maker is a firm that faces a downward-sloping demand curve. If it raises its price, it loses some buyers, but not all of them.
• Why MR < AR:
• To sell one more unit, the firm must cut its price.
• The lower price applies to every unit it sells, not only the extra one.

• So the extra revenue (MR) is less than the price (AR).

• Worked example:

• At ₹10, the firm sells 5 units: TR (total revenue) = ₹50.
• To sell 6 units, it must cut the price to ₹9: TR = ₹54.

• MR of the 6th unit = ₹54 − ₹50 = ₹4, but AR = ₹9. So MR < AR.

• Every structure except perfect competition has price makers. They differ only in how much price control they have.

4. The spectrum, from most to least competitive

Structure	Sellers	Product	Entry	Price control	Demand curve	Indian example
Perfect competition	Very many, small	Homogeneous	Free	None (price taker)	Horizontal, AR = MR	Wheat or vegetables in a farm mandi (close to it)
Monopolistic competition	Many	Differentiated	Free	Some	Downward-sloping, elastic	Restaurants, FMCG soap and shampoo brands
Oligopoly	Few, interdependent	Same or differentiated	High barriers	Considerable	Kinked or uncertain	Cement, aviation, steel
Duopoly	Two	Same or differentiated	High barriers	Considerable	Interdependent	Near-duopoly in private telecom
Monopoly	One	No close substitute	Blocked	High (price maker)	Market demand curve	Indian Railways (rail passenger service)

• Monopolistic competition. Many firms sell products that are close but not identical.
• Brand loyalty gives each firm a small, private demand curve that slopes down.
• Many close substitutes exist, so this curve is elastic (quantity reacts strongly to price).

• Entry is free, so in the long run profits fall back to normal.

• Oligopoly. A few large firms dominate the market.

• The key feature is interdependence: each firm's best price depends on what its rivals do.

• The kinked demand curve explains why prices stay fixed. If one firm raises its price, rivals do not follow and it loses buyers. If it cuts its price, rivals match the cut and it gains little. So prices tend to stay where they are.

• Duopoly. This is an oligopoly with exactly two sellers. Each firm's demand depends directly on the other's price or output.

• Monopoly. There is a single seller of a product with no close substitute, and entry is blocked.

• The firm's demand curve is the whole market demand curve.

• Buyer-side mirror. On the buyer side:

• Monopsony means a single buyer, for example one large employer in a small town.
• Oligopsony means a few buyers.
• Both give buyers power to push prices down (covered in Section 3).

5. Market power

• Market power is a firm's ability to raise its price above marginal cost (P > MC) and still make a profit without losing all its buyers.
• Marginal cost (MC) is the cost of making one more unit.

• Under perfect competition, P = MC in equilibrium. Any gap between P and MC is a rough sign of market power.

• Measuring the gap (Lerner index): L = (P − MC) / P.

• L = 0 for a price taker. L rises towards 1 as market power grows.

• Worked example: P = ₹100 and MC = ₹60 give L = 40/100 = 0.4.

• Why it matters. A firm with market power produces less and charges more than a competitive market would. Some buyers who value the good above its cost go without it. This loss is called deadweight loss, and it is one form of market failure.

6. Where market power comes from

Barriers to entry are obstacles that keep new firms out, so existing firms keep their power:

• Economies of scale. Average cost falls as output rises (cross-ref production-and-costs).
• Huge fixed costs, such as a rail network or a steel plant, make a small entrant's cost per unit too high.

• In the extreme case, one firm can serve the whole market most cheaply. This is a natural monopoly.

• Patents and copyrights. The law gives the inventor or author sole rights for a fixed period.

• Government licences. Examples are telecom spectrum and airport landing slots.
• Control of a key input. Examples are a mine, a pipeline or a port.
• Network effects. A product becomes more useful as more people use it, so the market leader keeps pulling users in (Section 10).
• Switching costs. Changing supplier costs the buyer time, money or data, which locks buyers in.
• Indian law lists similar barriers. When the Competition Commission of India (CCI) decides whether a firm is dominant, it looks at entry barriers: regulatory barriers, financial risk, high capital cost of entry, marketing and technical entry barriers, and economies of scale. It also looks at countervailing buying power (whether buyers are strong enough to push back) and at market structure and size [2].

Product differentiation

• Product differentiation means making a product look different from rivals' products through brand, quality, design or service.
• It gives a firm some price control even when there are many sellers. This is why a soap brand can charge ₹5 more than an unbranded soap and still keep loyal buyers.

7. Market power under Indian competition law

• Relevant market. Before measuring power, the CCI first defines the relevant market.
• Demand side: all substitutes that consumers would switch to if the price rose.
• Supply side: all producers who could quickly switch to making those substitutes [2].

• Why this matters: a firm's market share can look big or small depending on how widely the market is drawn.

• Dominant position. Under Section 4 of the Competition Act, 2002, a dominant position is a position of strength in the relevant market. It lets a firm:

• act independently of the competitive forces in the market; or

• affect its competitors or consumers in its own favour [2].

• Dominance itself is not illegal. Only its abuse is. Abuse includes:

• imposing unfair or discriminatory conditions or prices in buying or selling;
• limiting production or technical development;

• blocking market access for new firms, to the harm of consumers [2].

• Case example. The CCI found that the BCCI had abused its dominant position. It had used restrictions that denied others access to the market for organising professional domestic cricket leagues. The CCI imposed a penalty of ₹52.24 crore [3].

• Mergers that create market power (Competition (Amendment) Act, 2023):
• A merger or acquisition must be approved by the CCI if the deal value is more than ₹2,000 crore and the target has substantial business operations in India. This rule targets digital deals, where a firm's value lies in its data or ideas rather than its assets or turnover [4].
• The time limit for the CCI to decide on a merger was cut from 210 days to 150 days [4].
• Control now means the ability to exercise material influence over a firm's management, affairs or strategic commercial decisions [4].
• Settlement and commitment. The CCI can close a case against a firm accused of abuse of dominance or anti-competitive agreements:
  • through a settlement, which may involve a payment; or
  • through commitments, which may be structural (changing what the firm owns) or behavioural (changing how it acts) [4].
• These amendments followed the Competition Law Review Committee (2019) [4].

8. Measuring concentration

• Market concentration is how much of total output a few firms account for. High concentration is a warning sign of market power, but not proof of it.
• Concentration ratio (CR4): the combined market share of the four largest firms.

• CR4 = s₁ + s₂ + s₃ + s₄

• Herfindahl-Hirschman Index (HHI): the sum of the squared market shares of all firms.

• HHI = Σ (sᵢ)², with shares in per cent.

• It ranges from near 0 (many tiny firms, an atomistic market) to 10,000 (a monopoly: 100² = 10,000).

• Thresholds (US DOJ/FTC Merger Guidelines, 2023):

• HHI above 1,800 means the market is highly concentrated.
• A merger that raises HHI by more than 100 in such a market is presumed anti-competitive.

• The 2010 guidelines used 2,500 as the cut-off for highly concentrated.

• Worked example. Four firms hold shares of 40, 30, 20 and 10.

• CR4 = 40 + 30 + 20 + 10 = 100%.
• HHI = 1,600 + 900 + 400 + 100 = 3,000, which is highly concentrated.

• Compare ten equal firms of 10% each: HHI = 10 × 10² = 1,000, which is not concentrated.

• Why HHI beats CR4:

• Squaring gives extra weight to the biggest firms.
• Shares of 70-10-10-10 and 25-25-25-25 both have CR4 = 100%.
• Their HHIs are 5,200 (4,900 + 100 + 100 + 100) and 2,500 (4 × 625).
• CR4 cannot tell these two markets apart. HHI shows the first is far more dominated.

• CR4 also ignores the size of firms below the top four. HHI counts every firm.

• How a merger moves the HHI. Take the 40-30-20-10 market. If the firms with 20% and 10% merge:

• The new shares are 40, 30 and 30.
• The new HHI = 1,600 + 900 + 900 = 3,400.
• The rise is 400, well above 100, so the merger would be presumed anti-competitive under the 2023 guidelines.
• Shortcut: the rise always equals 2 × s₁ × s₂ = 2 × 20 × 10 = 400.

9. Indian telecom illustration

• Wireless (mobile) market, scaffold figures. Approximate shares are Jio ~41, Airtel ~33, Vi ~18 and BSNL ~8 (verify current).

• HHI ≈ 1,681 + 1,089 + 324 + 64 ≈ 3,160. This is highly concentrated under both the 2010 and 2023 cut-offs.

• Official data. At the end of May 2026, private operators held 92.71% of wireless subscribers. The public sector operators BSNL and MTNL together held 7.29% [5]. So the BSNL figure of about 8 in the scaffold is close to the current share.

• A sub-market can look very different: M2M connections (May 2026).
• M2M (machine-to-machine) connections are mobile links used by devices such as smart meters and vehicle trackers.
• Shares: Airtel 61.65%, Jio 19.14%, Vi 16.02%, BSNL 3.19% [5].
• HHI ≈ 3,801 + 366 + 257 + 10 ≈ 4,434, which is far more concentrated than the overall mobile market.
• Lesson: how the relevant market is drawn changes both the concentration figure and who leads the market.

Prelims Hooks

• Perfect competition has four features: many buyers and sellers, a homogeneous product, free entry and exit, and perfect information. Together they make each firm a price taker with AR = MR = p and a perfectly elastic (horizontal) demand curve.
• A price maker faces a downward-sloping demand curve, so MR < AR. To sell one more unit, it must cut the price on all units.
• Market power means P > MC. The Lerner index is (P − MC)/P, which is 0 under perfect competition.
• HHI = Σ(sᵢ)². The maximum is 10,000 (monopoly). Ten equal firms give 1,000. The 2023 US guidelines treat above 1,800 as highly concentrated (the 2010 cut-off was 2,500).
• Trap: two markets with the same CR4 (70-10-10-10 and 25-25-25-25) can have very different HHIs (5,200 and 2,500).
• Trap: under Section 4 of the Competition Act, 2002, being dominant is not an offence. Only abuse of a dominant position is [2].
• The Competition (Amendment) Act, 2023 added a ₹2,000 crore deal-value threshold for CCI approval of mergers and cut the approval time limit from 210 to 150 days [4].
• Monopsony means one buyer and oligopsony means a few buyers. Do not confuse them with monopoly and oligopoly, which are about sellers.
• The kinked demand curve belongs to oligopoly. It explains why prices stay fixed.
• The CCI fined the BCCI ₹52.24 crore for abuse of dominance in organising professional domestic cricket leagues [3].

Mains Points

• Scale versus competition. Industries like telecom, cement and aviation need huge fixed costs and scarce licences such as spectrum and airport slots. This makes some concentration unavoidable.
• Wireless HHI is about 3,160. Private firms held 92.71% of wireless subscribers at the end of May 2026 [5].

• Policy has to balance gains from scale against the risk of higher prices and weaker service. It also has to decide whether a public operator such as BSNL should be kept alive to stop a slide to a duopoly.

• Digital markets need new tools.

• Network effects, switching costs and control of data build market power even when prices are zero. Standard P > MC tests and turnover-based merger rules can miss this.

• The ₹2,000 crore deal-value threshold and the "material influence" test for control (2023) are India's answer to killer acquisitions, where big firms buy young rivals before they can grow [4].

• Structure versus conduct.

• Indian law punishes the abuse of dominance, not dominance itself [2]. This protects firms that grew big by being efficient.

• It also means cases take a long time. The settlement and commitment route (2023) lets the CCI fix harm faster, through behavioural or structural remedies [4].

• Defining the market is half the case.

• Concentration and dominance depend on where the relevant-market line is drawn, using demand-side and supply-side substitution [2].
• For example, Airtel's lead in M2M connections (61.65%) contrasts with Jio's lead in the overall mobile market [5]. This shows how a narrow market definition can make a firm look dominant, and a wide one can make it look ordinary.