Supply and Demand: Why Markets Tick

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In any market transaction between a seller and a buyer, the price of the good or service is determined by supply and demand in a market.
Supply is summarized by the supply curve: the quantities suppliers are willing to produce at each price. The higher the price, the more suppliers are likely to produce.
Demand is summarized by the demand curve: the quantities consumers are willing to buy at each price. The lower the price, the more consumers buy.
The intersection of the supply and demand curves represents the market-clearing price—the price at which demand and supply are the same.
Suppliers will keep producing as long as they can sell the good for a price that exceeds their marginal cost of production.
Buyers will purchase as long as the marginal utility of consumption exceeds the price.

Perfect competition:
- Large numbers of identical suppliers and demanders.
- Buyers and sellers can find one another at no cost.
- No barriers prevent new suppliers from entering the market.
- No individual agent can affect prices; both sides take the market price as given.
Monopoly and monopsony:
- Monopoly: one supplier of a good for which there is no simple substitute; the supplier can set price rather than take it as given.
- Monopsony: one buyer, usually a government, often facing many suppliers.
Intermediate market structures:
- Many markets fall between perfect competition and monopoly; in those cases, prices are higher and production is lower than under perfect competition.

The relationship between supply and demand and changes in price is called elasticity.
Inelastic goods are relatively insensitive to price changes; elastic goods are very responsive.
Examples:
- Energy is cited as a classic inelastic good (at least in the short term).
- Steak is cited as an elastic good.

Monopolies typically arise from natural or legal barriers to entry.
Utilities often operate as natural monopolies (inefficient for multiple firms to duplicate infrastructure).
Governments usually regulate such monopolies to ensure they do not abuse market power by setting prices too high.
Regulatory responses cited:
- Allow a company to operate as sole provider in return for requirements for minimum services to everyone.
- Caps on prices that can be charged, typically set to allow companies to recover fixed costs.

A monopolist faces the entire market demand curve and chooses output to maximize profit, typically resulting in:
- Higher prices than under perfect competition.
- Lower supply than under perfect competition.
Numerical illustration from the text:
- Firm in perfect competition: earns 5 cents a unit selling 1,000 units—or $50—in a total market of 100,000 units.
- If it lowers its price by 1 cent and gains an additional 1,000 units in sales, profits become $80 on sales of 2,000 units.
- Monopolist: controls all 100,000 units at a nickel a share, earning a profit of $5,000.
- If monopolist lowers price by a penny and increased demand by 1,000 units:
- That adds $40 to revenues.
- But loses a penny in profit on each of the 100,000 units previously sold—or $1,000.
Key outcome: monopolists usually set higher prices and restrict quantity relative to perfect competition.

Product variety allows substitution across types; differentiated products give producers limited market power even in competitive markets.
When main features are expensive to create but cheap to imitate (books, drugs, computer software), complications arise:
- High fixed costs and low marginal costs make imitation profitable for competitors.
- Governments often grant a temporary monopoly (copyright for books) so price exceeds marginal cost, allowing authors and publishers to recoup fixed costs and incentivize future production.

Production technologies, consumer preferences, and difficulties in matching sellers with buyers influence markets and determine the market-clearing price.
Prices can change for many reasons, including technology, consumer preference, and weather conditions.

Source: Supply and Demand: Why Markets Tick; F&D Magazine; Irena Asmundson.