A monopoly (from Greek and ) is a market in which one person or company is the only supplier of a particular good or service. A monopoly is characterized by a lack of economic competition to produce a particular thing, a lack of viable substitute goods, and the possibility of a high monopoly price well above the seller's marginal cost that leads to a high monopoly profit. The verb monopolise or monopolize refers to the process by which a company gains the ability to raise prices or exclude competitors. In economics, a monopoly is a single seller. In law, a monopoly is a business entity that has significant market power, that is, the power to charge overly high prices, which is associated with unfair price raises. Although monopolies may be big businesses, size is not a characteristic of a monopoly. A small business may still have the power to raise prices in a small industry (or market).

Market structures

Market structure is determined by the following factors:

  • Barriers to entry: Competition within the market will determine the firm's future profits, and future profits will determine the entry and exit barriers to the market. Estimating entry, exit and profits are decided by three factors: the intensity of competition in short-term prices, the magnitude of sunk costs of entry faced by potential entrants, and the magnitude of fixed costs faced by incumbents.
  • The number of companies in the market: If the number of firms in the market increases, the value of firms remaining and entering the market will decrease, leading to a high probability of exit and a reduced likelihood of entry.
  • Product substitutability: Product substitution is the phenomenon where customers can choose one product over another. This is the main way to distinguish a monopolistic competition market from a perfect competition market.

In economics, the idea of monopolies is important in the study of management structures, which directly concerns normative aspects of economic competition, and provides the basis for topics such as industrial organization and economics of regulation. There are four basic types of market structures in traditional economic analysis: perfect competition, monopolistic competition, oligopoly, and monopoly. A monopoly is a structure in which a single supplier produces and sells a given product or service. If there is a single seller in a certain market and there are no close substitutes for the product, then the market structure is that of a "pure monopoly". Sometimes, there are many sellers in an industry or there exist many close substitutes for the goods being produced, but nevertheless, companies retain some market power. This is termed "monopolistic competition", whereas in an oligopoly, the companies interact strategically.

In general, the main results from this theory compare the price-fixing methods across market structures, analyze the effect of a certain structure on welfare, and vary technological or demand assumptions in order to assess the consequences for an abstract model of society. Most economic textbooks follow the practice of carefully explaining the "perfect competition" model, mainly because this helps to understand departures from it (the so-called "imperfect competition" models).

The boundaries of what constitutes a market and what does not are relevant distinctions to make in economic analysis. In a general equilibrium context, a good is a specific concept including geographical and time-related characteristics. Most studies of market structure relax a little their definition of a good, allowing for more flexibility in the identification of substitute goods.

Characteristics

A monopoly has at least one of these five characteristics:

  • Profit maximizer: monopolists will choose the price or output to maximise profits at where MC=MR. This output will be somewhere over the price range, where demand is price elastic. If the total revenue is higher than total costs, the monopolists will make abnormal profits.
  • Price maker: Decides the price of the good or product to be sold, but does so by determining the quantity in order to demand the price desired by the firm.
  • High barriers to entry: Other sellers are unable to enter the market of the monopoly.
  • Single seller: In a monopoly, there is one seller of the good, who produces all the output. Therefore, the whole market is being served by a single company, and for practical purposes, the company is the same as the industry.
  • Price discrimination: A monopolist can change the price or quantity of the product. They sell higher quantities at a lower price in a very elastic market, and sell lower quantities at a higher price in a less elastic market.

Market power can be estimated with Lerner index. High profit margins might be caused by different factors, such as risk premiums or monopoly profits.

Monopolies can cause corruption or political bias.

Sources of monopoly power

Monopolies derive their market power from barriers to entry – circumstances that prevent or greatly impede a potential competitor's ability to compete in a market. There are three major types of barriers to entry: economic, legal, and deliberate.

  • Elasticity of demand: In a complete monopolistic market, the demand curve for the product is the market demand curve. There is only one firm within the industry. The monopolist is the sole seller, and its demand is the demand of the entire market. A monopolist is the price setter, but it is also limited by the law of market demand. If he/she sets a high price, the sales volume will inevitably decline; if they expand the sales volume, the price must be lowered, which means that the demand and price in the monopoly market move in opposite directions. Therefore, the demand curve faced by a monopoly is a downward-sloping curve or a negative slope. Since monopolists control the supply of the entire industry, they also control the price of the entire industry and become price setters. A monopolistic firm can have two business decisions: sell less output at a higher price or sell more output at a lower price. There are no close substitutes for the products of a monopolistic firm. Otherwise, other firms can produce substitutes to replace the monopoly firm's products, and a monopolistic firm cannot become the only supplier in the market. So consumers have no other choice.
  • Economic barriers: Economic barriers include economies of scale, capital requirements, competitive advantages, de facto standards, network effects, strategic entry deterrence, switching barriers, vendor lock-in, vertical integration and technological superiority.
  • Economies of scale: Decreasing unit costs for larger volumes of production. Decreasing costs coupled with large initial costs, If for example, the industry is large enough to support one company of minimum efficient scale then other companies entering the industry will operate at a size that is less than MES, and so cannot produce at an average cost that is competitive with the dominant company. And if the long-term average cost of the dominant company is constantly decreasing, then that company will continue to have the least cost method to provide a good or service.
  • Capital requirements: Production processes that require large investments of capital, perhaps in the form of large research and development costs or substantial sunk costs, limit the number of companies in an industry: this is an example of economies of scale.
  • Technological superiority: A monopoly may be better able to acquire, integrate, and use the best possible technology in producing its goods while entrants either do not have the expertise or are unable to meet the high fixed costs (see above) needed for the most efficient technology.
  • No substitute goods: A monopoly sells a good for which there is no close substitute. The absence of substitutes makes the demand for that good relatively inelastic, enabling monopolies to extract positive profits.
  • Control of natural resources: A prime source of monopoly power is the control of resources (such as raw materials) that are critical to the production of a final good.
  • Network externalities: The use of a product by a person can affect the value of that product to other people. This is the network effect. There is a direct relationship between the proportion of people using a product and the demand for that product. In other words, the more people who are using a product, the greater the probability that another individual will start to use the product. This reflects fads and fashion trends, social networks, etc. It can also play a crucial role in the development or acquisition of market power. The most famous current example is the market dominance of the Microsoft Office suite and operating system in personal computers. Market exit and shutdown are sometimes separate events. The decision of whether to shut down or operate is not affected by exit barriers. A company will shut down if the price falls below the minimum average variable costs.

Monopoly versus competitive markets

thumb|right|235px|This 1879 anti-monopoly cartoon depicts powerful railroad barons controlling the entire rail system.

While monopoly and perfect competition represent the extremes of market structures. There is some similarity. The cost functions are the same. Both monopolies and perfectly competitive (PC) companies minimize cost and maximize profit. The shutdown decisions are the same. Both are assumed to have perfectly competitive factor markets. There are distinctions; some of the most important are as follows:

  • Marginal revenue and price: In a perfectly competitive market, price equals marginal cost. In a monopolistic market, however, price is set above marginal cost. The price equals marginal revenue in this case.
  • Product differentiation: There is no product differentiation in a perfectly competitive market. Every product is perfectly homogeneous and a perfect substitute for any other. With a monopoly, there is great to absolute product differentiation in the sense that there is no available substitute for a monopolized good. The monopolist is the sole supplier of the good in question. A customer either buys from the monopolizing entity on its terms or does without.
  • Number of competitors: PC markets are populated by a large number of buyers and sellers. A monopoly involves a single seller.
  • Excess profits: Excess or positive profits are profit more than the normal expected return on investment. A PC company can make excess profits in the short term but excess profits attract competitors, which can enter the market freely and decrease prices, eventually reducing excess profits to zero. A monopoly can preserve excess profits because barriers to entry prevent competitors from entering the market.
  • Profit maximization: A PC company maximizes profits by producing such that price equals marginal costs. A monopoly maximises profits by producing where marginal revenue equals marginal costs. The rules are not equivalent. The demand curve for a PC company is perfectly elastic – flat. The demand curve is identical to the average revenue curve and the price line. Since the average revenue curve is constant, the marginal revenue curve is also constant and equals the demand curve, Average revenue is the same as price (<math>\text{AR} = \frac{\text{TR{Q} = P \cdot \frac{Q}{Q} = P</math>). Thus, the price line is also identical to the demand curve. In sum, <math>\text{D} = \text{AR} = \text{MR} = P</math>.
  • P-Max quantity, price and profit: If a monopolist obtains control of a formerly perfectly competitive industry, the monopolist would increase prices, reduce production, incur deadweight loss, and realise positive economic profits.
  • Supply curve: in a perfectly competitive market, there is a well-defined supply function with a one-to-one relationship between price and quantity supplied. In a monopolistic market, no such supply relationship exists. A monopolist cannot trace a short-term supply curve because for a given price, there is not a unique quantity supplied. As Pindyck and Rubenfeld note, a change in demand "can lead to changes in prices with no change in output, changes in output with no change in price, or both" Monopolies produce where marginal revenue equals marginal costs. For a specific demand curve, the supply "curve" would be the price-quantity combination at the point where marginal revenue equals marginal cost. If the demand curve shifted, the marginal revenue curve would shift as well, and a new equilibrium and supply "point" would be established. The locus of these points would not be a supply curve in any conventional sense.

The most significant distinction between a PC company and a monopoly is that the monopoly has a downward-sloping demand curve rather than the "perceived" perfectly elastic curve of the PC company. Practically all the variations mentioned above relate to this fact. If there is a downward-sloping demand curve, then by necessity there is a distinct marginal revenue curve. The implications of this fact are best made manifest with a linear demand curve. Assume that the inverse demand curve is of the form <math>x = a-by </math>. Then the total revenue curve is <math>\text{TR} = ay - by^2</math> and the marginal revenue curve is thus <math>\text{MR} = a - 2by</math>. From this several things are evident. First, the marginal revenue curve has the same <math>x</math>-intercept as the inverse demand curve. Second, the slope of the marginal revenue curve is twice that of the inverse demand curve. What is not quite so evident is that the marginal revenue curve is below the inverse demand curve at all points (<math>y \ge 0</math>). Total revenue equals price times quantity. A competitive company has a perfectly elastic demand curve meaning that total revenue is proportional to output. Total revenue has its maximum value when the slope of the total revenue function is zero. The slope of the total revenue function is marginal revenue. So the revenue maximizing quantity and price occur when <math>\text{MR} = 0</math>. For example, assume that the monopoly's demand function is <math>P = 50 - 2Q</math>. The total revenue function would be <math>\text{TR} = 50Q - 2Q^2</math> and marginal revenue would be <math>50 - 4Q</math>. Setting marginal revenue equal to zero we have

: <math> 50-4Q=0</math>

: <math>-4Q=-50</math>

: <math>Q = 12.5</math>

So the revenue maximizing quantity for the monopoly is 12.5 units and the revenue-maximizing price is 25.

A company with a monopoly does not experience price pressure from competitors, although it may experience pricing pressure from potential competition. If a company increases prices too much, then others may enter the market if they are able to provide the same good, or a substitute, at a lesser price. The idea that monopolies in markets with easy entry need not be regulated against is known as the "revolution in monopoly theory".

A monopolist can extract only one premium, and getting into complementary markets does not pay. That is, the total profits a monopolist could earn if it sought to leverage its monopoly in one market by monopolizing a complementary market are equal to the extra profits it could earn anyway by charging more for the monopoly product itself. However, the one monopoly profit theorem is not true if customers in the monopoly good are stranded or poorly informed, or if the tied good has high fixed costs.

A pure monopoly has the same economic rationality of perfectly competitive companies, i.e. to optimise a profit function given some constraints. By the assumptions of increasing marginal costs, exogenous inputs' prices, and control concentrated on a single agent or entrepreneur, the optimal decision is to equate the marginal cost and marginal revenue of production. Nonetheless, a pure monopoly can – unlike a competitive company – alter the market price for its own convenience: a decrease of production results in a higher price. In the economics' jargon, it is said that pure monopolies have "a downward-sloping demand". An important consequence of such behaviour is that typically a monopoly selects a higher price and lesser quantity of output than a price-taking company; again, less is available at a higher price.

Inverse elasticity rule

A monopoly chooses that price that maximizes the difference between total revenue and total cost. The basic markup rule (as measured by the Lerner index) can be expressed as

<math>\frac{P - MC}{P} = \frac{-1}{E_d}</math>,

where <math>E_d</math> is the price elasticity of demand the firm faces. The markup rules indicate that the ratio between profit margin and the price is inversely proportional to the price elasticity of demand. Perfectly competitive (PC) companies have zero market power when it comes to setting prices. All companies of a PC market are price takers. The price is set by the interaction of demand and supply at the market or aggregate level. Individual companies simply take the price determined by the market and produce that quantity of output that maximizes the company's profits. If a PC company attempted to increase prices above the market level all its customers would abandon the company and purchase at the market price from other companies. A monopoly has considerable although not unlimited market power. A monopoly has the power to set prices or quantities although not both. A monopoly is a price maker. The monopoly is the market and prices are set by the monopolist based on their circumstances and not the interaction of demand and supply. The two primary factors determining monopoly market power are the company's demand curve and its cost structure.

Market power is the ability to affect the terms and conditions of exchange so that the price of a product is set by a single company (price is not imposed by the market as in perfect competition). Although a monopoly's market power is great it is still limited by the demand side of the market. A monopoly has a negatively sloped demand curve, not a perfectly inelastic curve. Consequently, any price increase will result in the loss of some customers.

Price discrimination

Price discrimination allows a monopolist to increase its profit by charging higher prices for identical goods to those who are willing or able to pay more. For example, most economic textbooks cost more in the United States than in developing countries like Ethiopia. In this case, the publisher is using its government-granted copyright monopoly to price discriminate between the generally wealthier American economics students and the generally poorer Ethiopian economics students. Similarly, most patented medications cost more in the U.S. than in other countries with a (presumed) poorer customer base. Typically, a high general price is listed, and various market segments get varying discounts. This is an example of framing to make the process of charging some people higher prices more socially acceptable. Perfect price discrimination would allow the monopolist to charge each customer the exact maximum amount they would be willing to pay. This would allow the monopolist to extract all the consumer surplus of the market. A domestic example would be the cost of airplane flights in relation to their takeoff time; the closer they are to flight, the higher the plane tickets will cost, discriminating against late planners and often business flyers. While such perfect price discrimination is a theoretical construct, advances in information technology and micromarketing may bring it closer to the realm of possibility.

Partial price discrimination can cause some customers who are inappropriately pooled with high price customers to be excluded from the market. For example, a poor student in the U.S. might be excluded from purchasing an economics textbook at the U.S. price, which the student may have been able to purchase at the Ethiopian price. Similarly, a wealthy student in Ethiopia may be able to or willing to buy at the U.S. price, though naturally would hide such a fact from the monopolist so as to pay the reduced third world price. These are deadweight losses and decrease a monopolist's profits. Deadweight loss is considered detrimental to society and market participation. As such, monopolists have substantial economic interest in improving their market information and market segmenting.

There is important information for one to remember when considering the monopoly model diagram (and its associated conclusions) displayed here. The result that monopoly prices are higher, and production output lesser, than a competitive company follow from a requirement that the monopoly not charge different prices for different customers. That is, the monopoly is restricted from engaging in price discrimination (this is termed first degree price discrimination, such that all customers are charged the same amount). If the monopoly were permitted to charge individualised prices (this is termed third degree price discrimination), the quantity produced, and the price charged to the marginal customer, would be identical to that of a competitive company, thus eliminating the deadweight loss; however, all gains from trade (social welfare) would accrue to the monopolist and none to the consumer. In essence, every consumer would be indifferent between going completely without the product or service and being able to purchase it from the monopolist.

As long as the price elasticity of demand for most customers is less than one in absolute value, it is advantageous for a company to increase its prices: it receives more money for fewer goods. With a price increase, price elasticity tends to increase, and in the optimum case above it will be greater than one for most customers.

A company maximizes profit by selling where marginal revenue equals marginal cost. A company that does not engage in price discrimination will charge the profit maximizing price, <math>P^*</math>, to all its customers. In such circumstances there are customers who would be willing to pay a higher price than <math>P^*</math> and those who will not pay <math>P^*</math> but would buy at a lower price. A price discrimination strategy is to charge less price sensitive buyers a higher price and the more price sensitive buyers a lower price. Thus additional revenue is generated from two sources. The basic problem is to identify customers by their willingness to pay.

The purpose of price discrimination is to transfer consumer surplus to the producer. Consumer surplus is the difference between the value of a good to a consumer and the price the consumer must pay in the market to purchase it. Price discrimination is not limited to monopolies.

Market power is a company's ability to increase prices without losing all its customers. Any company that has market power can engage in price discrimination. Perfect competition is the only market form in which price discrimination would be impossible (a perfectly competitive company has a perfectly elastic demand curve and has no market power).

There are three forms of price discrimination. First degree price discrimination charges each consumer the maximum price the consumer is willing to pay. Second degree price discrimination involves quantity discounts. Third degree price discrimination involves grouping consumers according to willingness to pay as measured by their price elasticities of demand and charging each group a different price. Third degree price discrimination is the most prevalent type.

There are three conditions that must be present for a company to engage in successful price discrimination. First, the company must have market power. Second, the company must be able to sort customers according to their willingness to pay for the good. Third, the firm must be able to prevent resell.

A company must have some degree of market power to practice price discrimination. Without market power a company cannot charge more than the market price. Any market structure characterized by a downward sloping demand curve has market power – monopoly, monopolistic competition and oligopoly. Direct information about a consumer's willingness to pay is rarely available. Sellers tend to rely on secondary information such as where a person lives (postal codes); for example, catalog retailers can use mail high-priced catalogs to high-income postal codes. First degree price discrimination most frequently occurs in regard to professional services or in transactions involving direct buyer-seller negotiations. For example, an accountant who has prepared a consumer's tax return has information that can be used to charge customers based on an estimate of their ability to pay.

In second degree price discrimination or quantity discrimination customers are charged different prices based on how much they buy. There is a single price schedule for all consumers but the prices vary depending on the quantity of the good bought. The theory of second degree price discrimination is a consumer is willing to buy only a certain quantity of a good at a given price. Companies know that consumer's willingness to buy decreases as more units are purchased. The task for the seller is to identify these price points and to reduce the price once one is reached in the hope that a reduced price will trigger additional purchases from the consumer. For example, sell in unit blocks rather than individual units.

In third degree price discrimination or multi-market price discrimination the seller divides the consumers into different groups according to their willingness to pay as measured by their price elasticity of demand. Each group of consumers effectively becomes a separate market with its own demand curve and marginal revenue curve. Generally the company charges a higher price to the group with a more price inelastic demand and a relatively lesser price to the group with a more elastic demand. Examples of third degree price discrimination abound. Airlines charge higher prices to business travelers than to vacation travelers. The reasoning is that the demand curve for a vacation traveler is relatively elastic while the demand curve for a business traveler is relatively inelastic. Any determinant of price elasticity of demand can be used to segment markets. For example, seniors have a more elastic demand for movies than do young adults because they generally have more free time. Thus theaters will offer discount tickets to seniors.

Example

Assume that by a uniform pricing system the monopolist would sell five units at a price of $10 per unit. Assume that his marginal cost is $5 per unit. Total revenue would be $50, total costs would be $25 and profits would be $25. If the monopolist practiced price discrimination he would sell the first unit for $17 the second unit for $14 and so on which is listed in the table below. Total revenue would be $55, his total cost would be $25 and his profit would be $30. Several things are worth noting. The monopolist acquires all the consumer surplus and eliminates practically all the deadweight loss because he is willing to sell to anyone who is willing to pay at least the marginal cost. Thirdly, the discriminating monopolist produces a larger quantity than the monopolist operating by a uniform pricing scheme.

{| class="wikitable"

|-

!Qd !! Price

|-

| 1 || $17

|-

| 2 || $14

|-

| 3 || $11

|-

| 4 || $8

|-

| 5 || $5

|}

Classifying customers

Successful price discrimination requires that companies separate consumers according to their willingness to buy. Determining a customer's willingness to buy a good is difficult. Asking consumers directly is fruitless: consumers do not know, and to the extent they do they are reluctant to share that information with marketers. The two main methods for determining willingness to buy are observation of personal characteristics and consumer actions. As noted information about where a person lives (postal codes), how the person dresses, what kind of car he or she drives, occupation, and income and spending patterns can be helpful in classifying.

Monopoly and efficiency

thumb|upright=2|right|In a competitive market, everything above the horizontal line at Pc would be consumer surplus, and everything below, producer surplus. The monopolist pushes up the price (from Pc to Pm), reducing consumption (from Qc to Qm) but capturing some of the consumer surplus. The remaining consumer surplus is shown in red; the enlarged producer surplus in blue. But increasing the price means price-sensitive consumers do not buy, causing a [[deadweight loss (in yellow). Since the yellow area below line Pc (what the monopolist loses from lower sales) is smaller than the blue area above line Pc (what the monopolist gains from higher prices), the monopolist has a net gain, but society has a net loss; economic efficiency decreases. ]]