Market structure — competition to monopoly

Market structure — how many firms, how differentiated their products, how easy entry — determines pricing, output, profit, and welfare. The textbook spectrum runs from perfect competition (many firms, identical product, free entry) to monopoly (one firm, no substitute, blocked entry). African markets are concentrated more often than the textbook benchmark; understanding the implications is the operational point of this module.

Perfect competition

The reference benchmark. Assumptions:

• Many buyers, many sellers — none individually large enough to affect price
• Homogeneous product — buyers are indifferent between any seller's output
• Free entry and exit — no barriers to firms joining or leaving
• Perfect information — buyers and sellers know prices and quality

Under perfect competition, every firm is a price-taker: it can sell as much as it wants at the prevailing market price. In equilibrium, profit-max gives P = MC (price equals marginal cost). With free entry, long-run profit is competed away to zero (above-normal profit attracts entrants until equilibrium has P = AC as well).

Welfare implications: perfect competition delivers allocative efficiency (P = MC means consumers value the last unit at exactly what it costs to produce it) and productive efficiency (P = AC means firms operate at minimum average cost in the long run). Consumer surplus + producer surplus is maximised.

Monopoly

One firm, no close substitutes, blocked entry. The monopolist faces the entire market demand curve. To sell more, must lower price — so marginal revenue (MR) is less than price (P). Profit-max where MR = MC, giving P > MC at the optimum.

Deadweight loss from monopoly

At the monopoly equilibrium, the quantity transacted is below the competitive quantity. Some mutually-beneficial trades (where buyer's willingness-to-pay exceeds marginal cost) don't occur. The lost gains-from-trade is the deadweight loss.

Monopolistic competition

Many firms, but each produces a slightly differentiated product. Each firm faces a downward-sloping demand curve (because of differentiation) — like a small monopoly — but free entry drives long-run profit to zero. The result is firms at long-run zero profit but with prices above marginal cost.

Restaurant industry, retail clothing, consumer-services markets in most cities — all monopolistic competition. Some inefficiency (P > MC) but no large deadweight loss because each firm faces meaningful competition.

Oligopoly

Few firms (2-10), each large enough to affect price, with strategic interdependence — each firm's optimal decision depends on what the others do.

• Cournot competition — firms choose quantities; price clears the market given total quantity. Stable equilibrium between competitive and monopoly outcomes. More firms → more competitive
• Bertrand competition — firms choose prices; the lower-price firm captures the market. With homogeneous products, price equals marginal cost (the 'Bertrand paradox'). With differentiated products, prices stay above MC
• Stackelberg competition — sequential moves (leader-follower). The leader has an advantage; the leader's commitment shifts the follower's best-response curve
• Repeated games — when firms interact period after period, cooperative (collusive) outcomes become sustainable. The 'tit-for-tat' strategies in repeated prisoners' dilemmas

Natural monopoly

Some industries have a cost structure such that one firm can produce the entire industry output at lower total cost than any number of smaller firms. Conditions:

• Large fixed costs and small marginal costs — telecommunications, electricity transmission, water utilities, rail networks
• Significant scale economies that extend through the entire relevant market — small competitors can't reach efficient scale

Natural monopolies create the regulatory dilemma: competition is inefficient (duplicate infrastructure raises costs) but unregulated monopoly is exploitative (P > MC; deadweight loss). The standard response:

• Public ownership — the state operates the natural monopoly. Historically common (Kenya Power, Kenya Pipeline, Kenya Railways). Concerns about state inefficiency and political interference
• Public regulation of private operator — the state allows a private firm to operate but regulates prices, quality, and entry. Common modern approach. Kenya's Energy and Petroleum Regulatory Authority (EPRA), Communications Authority (CA), Insurance Regulatory Authority all do this
• Competition with regulated access — allow multiple operators but require the natural-monopoly element (network, infrastructure) to be shared on regulated terms. Telecom interconnection regulations work this way

Concentration in Kenyan banking

Kenya banking is a study in concentration. The Central Bank classifies banks into Tier I, II, III by size:

• Tier I — 8 banks with KES 40+ billion in deposits. KCB, Equity, Coop Bank, Standard Chartered, Stanbic, Absa, NCBA, DTB. ~75% of total banking assets
• Tier II — 16 banks with KES 5-40 billion. ~20% of assets
• Tier III — 14 banks below KES 5 billion. ~5% of assets

The lending-deposit spread (the difference between what banks charge to lend and pay on deposits) has averaged 9.5 percentage points over 34 years — among the highest in Africa and well above OECD comparators (typically 2-4 pp). The spread captures both legitimate costs (operational, capital, default risk) and oligopoly rents.

Concentration in Kenyan telecoms

Kenya mobile-money and mobile-voice markets are dominated by Safaricom (~65% market share for voice; ~95% market share for mobile-money). Airtel and Telkom collectively hold the residual.

The dominance is partly natural-monopoly (network effects in mobile-money; capex-heavy network deployment) and partly first-mover-advantage (M-Pesa launched 2007, established a near-impossible-to-replicate user base).

Regulatory responses:

• Communications Authority interventions — interconnection rate regulation; spectrum allocation; market-power designations. Effects modest because the network effects are the binding force
• Mobile-money interoperability — Kenya's 2022 interoperability rules require cross-network transfers at reasonable rates. Effects emerging
• Bank-fintech access — opening API-level access to mobile-money services. Reduces switching costs for users; should erode Safaricom dominance over time