Market failure is a situation in economics in which a market allocates resources inefficiently. In its standard technical meaning, the resulting allocation is not Pareto efficient: an alternative feasible allocation could make someone better off without making anyone worse off. Market failure does not necessarily mean that trading stops or businesses fail. Markets may function continuously while producing too much of some activities, too little of others, or excluding mutually beneficial exchanges. The concept is central to welfare economics and the analysis of public policy. (books.core-econ.org)
Efficiency and the competitive benchmark
Models of perfect competition provide a benchmark for assessing market outcomes. When participants take prices as given, contracts adequately cover relevant interactions, and production and consumption do not impose uncompensated effects on outsiders, a competitive market equilibrium can allocate resources efficiently. Prices coordinate individual decisions, encouraging exchanges whose benefits exceed their costs. Market failure arises when conditions underlying this result are absent, rather than simply because an outcome is unpopular. (books.core-econ.org)
Efficiency is distinct from fairness. An efficient allocation may coexist with substantial income inequality, because purchasing power and initial resources affect who receives goods. Conversely, redistribution can be motivated by equity without requiring evidence of market failure. Assessing a market therefore involves separate questions about whether gains from exchange remain unrealized and whether the distribution of those gains is acceptable. (books.core-econ.org)
Externalities
An externality occurs when an activity affects others in ways not fully reflected in prices or compensation. Negative externalities, such as pollution, create a gap between private and social costs. A producer considering only its own expenses may expand output beyond the socially efficient level because some costs fall on third parties. Positive externalities create the opposite problem: decision-makers may undertake too little activity because they cannot capture all its benefits. (imf.org)
Research and development illustrates positive externalities through knowledge spillovers: discoveries can benefit firms and individuals other than those financing the research. In a simple competitive model, efficient output equates marginal social benefit with marginal social cost. Private decisions instead compare private benefits with private marginal costs, potentially producing a different quantity. The relevant inefficiency is this divergence, not merely the existence of an effect on others. (imf.org)
Public goods and shared resources
A public good is non-excludable and non-rival: people cannot readily be prevented from benefiting, and one person's use does not reduce what remains available to others. These characteristics create a free-rider problem. Individuals can benefit without contributing, weakening incentives for voluntary financing even when the combined benefits exceed provision costs. National defense and some forms of publicly available knowledge illustrate this problem. Public goods are defined by their characteristics, not by whether government supplies them. (imf.org)
Common-pool resources differ because use is rival although exclusion is difficult. Fish in an open-access fishery, for example, are unavailable to others once caught. Users may overlook the costs their extraction imposes on other users, encouraging depletion. Public-good problems typically concern insufficient provision; common-resource problems typically concern excessive use. Ownership arrangements and collective rules can alter these incentives. (books.core-econ.org)
Market power
Market power allows a firm or buyer to influence prices rather than accept them. In the standard single-price monopoly model, a profit-maximizing seller restricts output and charges a price above marginal cost. Some transactions that would generate benefits exceeding production costs consequently do not occur, creating deadweight loss. The transfer of income from buyers to the seller is analytically distinct from this loss of potential gains. (books.core-econ.org)
A natural monopoly arises when cost conditions make supplying a market through one producer cheaper than dividing production among competing firms. Large fixed costs and declining average costs can make competition difficult to sustain. This creates a policy trade-off: fragmented production may waste resources, while a sole supplier may exercise market power. (books.core-econ.org)
Information and missing exchanges
Information asymmetry exists when one party knows relevant facts unavailable to another. Adverse selection concerns hidden characteristics affecting participation. In the used-car example developed by George Akerlof, buyers unable to distinguish quality may offer prices that discourage owners of good cars from selling. The resulting deterioration in offered quality can shrink the market or, under particular assumptions, eliminate exchange. (nobelprize.org)
Moral hazard concerns actions that another party cannot adequately observe or enforce through a contract. Borrowers, employees, or insured parties may make decisions whose consequences partly fall on others. These problems can obstruct mutually beneficial contracts and contribute to incomplete markets. Reputation, warranties, signaling, and appropriately designed contracts can mitigate information problems, but do not invariably eliminate them. (books.core-econ.org)
Institutional responses and their limits
Responses depend on the mechanism involved. A Pigouvian tax seeks to align private incentives with external costs; subsidies may address external benefits. Public financing can support public goods, while economic regulation can address market power. Bargaining may internalize external effects when property rights are clear and transaction costs are sufficiently low. (imf.org)
Identifying market failure does not establish that a particular intervention improves outcomes. Authorities may lack information, enforcement capacity, or incentives to implement an effective response. Government failure describes shortcomings of public decision-making, although definitions vary. Policy analysis therefore compares feasible institutional alternatives, including their administrative costs, behavioral effects, and distributional consequences, rather than comparing an imperfect market with an assumed perfect government. (books.core-econ.org)