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IB DP Economics Study Notes

2.11.3 Monopolistic Competition

Monopolistic competition is a pivotal concept within microeconomics, offering a balance between the polar extremes of perfect competition and pure monopoly. This in-depth exploration will focus on its definition, core characteristics, and the variation in outcomes between the short and long-run.


Monopolistic competition refers to a market structure where multiple firms produce and sell products that, while not identical, are similar in nature. This situation is in stark contrast with:

  • Perfect Competition: Where numerous firms sell an indistinguishable product.
  • Monopoly: Where a singular firm holds the market, producing a unique, unmatched product. For a deeper understanding, see the page on Monopoly.

Additionally, it is worthwhile to compare this market structure with Oligopoly, which presents a scenario where a few firms dominate the market, detailed on the Oligopoly page.


Monopolistic competition is distinctly characterised by several pivotal features:

1. Many Sellers and Buyers: In this structure, a multitude of sellers exist, each commanding a relatively minor market share. Additionally, numerous buyers with diverse preferences populate the market, each seeking products that best match their individual needs.

2. Product Differentiation: Every firm in this market structure produces a product distinct from its competitors. This distinction can either be tangible (like quality, features, or design) or intangible (arising from branding or marketing strategies). This concept ties closely with the discussion on Non-price determinants of demand and Non-price determinants of supply, which further elaborate on how factors other than price affect market dynamics.

3. Freedom of Entry and Exit: The industry is very welcoming; firms can effortlessly enter or leave based on prospective profits or impending losses.

4. Limited Price Power: Owing to product differentiation, firms possess the discretion to set their prices. However, because close substitutes are available, this price-setting power is not unbridled.

5. Non-Price Competition: Instead of competing merely on price, firms frequently utilise advertising, promotions, and other non-price strategies to amplify the perceived value of their offerings. An in-depth analysis of strategies beyond price adjustments can be found in the Price Discrimination section.

An image illustrating the examples of monopolistic competition

Image courtesy of educba

Short-run vs. Long-run Outcomes

Short-run Outcomes

In the transitory phase of the short run, firms in monopolistic competition can experience a range of financial outcomes:

1. Abnormal Profits: When a firm's average total cost (ATC) is below the selling price, it enjoys an abnormal profit. To maximise profit, the firm will adjust production so its marginal cost (MC) aligns with its marginal revenue (MR).

A graph of short run abnormal profit in monopolistic competition

A graph illustrating short run abnormal profit in monopolistic competition.

Image courtesy of economicsonline

2. Normal Profits: A state of equilibrium is reached when the product price matches the ATC at the maximum profit output level, allowing the firm to break even and earn a customary profit.

3. Losses: If the set product price falls beneath the ATC at the optimal output level, the firm faces a loss. Depending on the severity of this financial setback, the firm may opt to persevere in hopes of improved future conditions, or alternatively, temporarily halt operations.

Long-run Outcomes

Monopolistic competition yields several unique outcomes in the enduring phase of the long run:

1. Zero Economic Profit: Short-run abnormal profits act as a beacon, luring new firms to the industry. As these new entrants establish themselves, existing firms find their product demand dwindling, which in turn forces a reduction in product price. This cycle persists until all excess profits are neutralised, with firms eventually earning just a normal profit. Conversely, if firms face losses, some may opt to exit, subsequently elevating demand and price for the survivors until they too reach a break-even point.

A graph of long run normal profit in monopolistic competition

A graph illustrating long run normal profit in monopolistic competition.

Image courtesy of economicsonline

2. Excess Capacity: Firms under monopolistic competition routinely operate with surplus capacity in the long run. Their production volume falls short of the level that would most efficiently reduce average costs. This anomaly arises due to the limited market power conferred by product differentiation, which allows firms to set prices higher than the MC.

3. Product Diversity: A notable upside of long-term monopolistic competition is the breadth of product variety. As firms continually innovate and differentiate to cater to a spectrum of consumer preferences, the market flourishes with a diverse array of products, each tailored to specific consumer segments.

4. Inefficiencies: Monopolistic competition, while promoting diversity, can lead to inefficiencies. Firms may not produce at the minimum point of their average cost curves, leading to allocative inefficiency. Additionally, the emphasis on non-price competition might result in excessive resources devoted to advertising or branding, which doesn't necessarily enhance consumer welfare.

5. Consumer Sovereignty: One of the major benefits for consumers in such a market is the power of choice. The vast array of differentiated products means consumers can choose products that closely align with their preferences, effectively granting them a degree of sovereignty in their purchasing decisions.

In essence, monopolistic competition occupies a unique space within the world of microeconomics. Characterised by its blend of competition and limited monopoly power, firms can relish abnormal profits in the transient short run. However, the dynamics of market entry and exit ensure a level playing field in the long run, where firms gravitate towards normal profits. While this might lead to some inefficiencies, it undeniably bestows consumers with a wealth of choices, catering to their diverse preferences.


Monopolistic competition can lead to an inefficient allocation of resources. Since firms have some degree of market power, they don't produce at the point where marginal cost equals marginal revenue, which is the most efficient level of production in terms of resource allocation. Instead, production occurs where marginal cost is less than price, leading to underproduction from the socially optimal level. This results in what's called 'excess capacity', where firms don't produce as much as they could at the minimum average total cost. Thus, resources that could have been utilised to produce more or cater to other sectors might remain underused in a monopolistically competitive market.

In monopolistic competition, firms tend not to achieve economies of scale to a significant degree because of their preference for product differentiation and the resultant excess capacity. Firms in this market structure often produce below the output level that would minimise average costs. By choosing not to produce at a level that fully utilises potential economies of scale, they sacrifice some efficiency. The reason behind this choice is their desire to maintain a unique position in the market and avoid becoming too similar to competitors, which could erode the differentiated status of their product.

The dynamic nature of monopolistic competition – with new firms entering and leaving, and constant product differentiation – means that firms must continuously adapt and innovate. For firms, this dynamism means they can't rest on their laurels; they must keep up with market trends, consumer preferences, and the strategies of their competitors. This perpetual need to adapt can lead to innovation and the continuous introduction of new products or improvements. For consumers, this dynamism can be beneficial as they get access to newer, better, or more varied products over time. However, it also means that brand loyalty can be fickle, and what's popular or preferred today might not be so tomorrow.

Product differentiation in a monopolistically competitive market enriches consumer choice. As firms strive to distinguish their products through branding, quality, features, or services, consumers gain access to a variety of options that cater to different preferences, needs, and budgets. This varied product landscape contrasts with a perfectly competitive market, where products are homogeneous. The result is a market where consumers can express brand loyalty, make purchases based on particular features or services, and derive satisfaction from products that feel more tailored to individual desires. However, it's worth noting that this differentiation can sometimes be more perceived than real, influenced heavily by advertising and branding strategies.

Firms in monopolistic competition often engage in non-price competition because they aim to differentiate their products from those of competitors. Non-price competition includes strategies such as advertising, product branding, quality improvements, and service enhancements. Since products in monopolistic competition are close substitutes but not identical, establishing brand loyalty or a perceived difference in quality can lead to a competitive edge. This type of competition allows firms to potentially earn higher profits without reducing prices. Furthermore, it helps maintain profit margins, reduce the price elasticity of demand, and potentially insulate the firm from price wars, which can erode profits rapidly.

Practice Questions

Define monopolistic competition and identify two key characteristics that differentiate it from perfect competition and monopoly.

Monopolistic competition refers to a market structure in which multiple firms produce and sell products that are close, but not perfect, substitutes for one another. Two defining characteristics of monopolistic competition are:

1. Product differentiation, which means that even though products are similar, they aren't perfect substitutes, often because of brand loyalty, perceived quality, or other unique selling propositions.

2. Freedom of entry and exit, which means that there aren't prohibitive barriers to new firms entering the market or existing firms leaving it. This characteristic distinguishes it from monopoly where high barriers to entry exist and from perfect competition where products are homogeneous.

Discuss the outcomes of monopolistic competition in the long run.

In the long run, monopolistic competition tends to lead to a situation where firms earn zero economic profit. This is because if firms in the short run earn abnormal profits, it attracts new firms to enter the market due to low barriers to entry. As more firms enter, the demand for existing firms reduces, leading to a decline in prices until all firms are just covering their costs, leading to normal profits. Additionally, a unique outcome of monopolistic competition in the long run is excess capacity, where firms operate below the level that minimises average costs. This happens because of their limited market power, which allows them to set prices higher than the marginal cost, yet lower than the level which maximises productive efficiency.

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Written by: Dave
Cambridge University - BA Hons Economics

Dave is a Cambridge Economics graduate with over 8 years of tutoring expertise in Economics & Business Studies. He crafts resources for A-Level, IB, & GCSE and excels at enhancing students' understanding & confidence in these subjects.

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