Oligopoly Market Structure: Kinked Demand Curve Explained | Economics

Collusion occurs when oligopolistic firms cooperate rather than compete, acting like a monopoly to maximize joint profits. A cartel is an explicit agreement among firms to set prices and output levels collectively. The OPEC oil cartel exemplifies this, where member countries coordinate production quotas to influence global oil prices. Collusion can be explicit (formal agreements) or tacit (coordinated behavior without direct communication).

Collusion in oligopoly refers to firms working together to maximize joint profits: (1) Firms form cartels or syndicates to fix prices and output collectively, (2) They coordinate their strategies to avoid competing with each other, (3) The goal is to maximize profits by acting like a monopoly, (4) However, collusion is unstable because individual firms have incentives to cheat (undercut prices secretly), (5) Regulatory bodies monitor and sometimes break up cartels, (6) Examples include OPEC (Organization of Petroleum Exporting Countries) as a successful cartel.

A cartel is a formal agreement among firms to collude and produce monopoly output. Cartels are illegal in the US and EU but exist elsewhere. OPEC (Organization of Petroleum Exporting Countries) is the most famous cartel, where oil-producing nations work together to set quantities and control prices. This demonstrates how oligopolistic firms can coordinate to act like a monopoly.

Firms in oligopolistic markets can behave in two fundamentally different ways: cooperatively or non-cooperatively. When firms cooperate, they form cartels—cooperative organizations of otherwise competing firms that collectively act as a single monopolist. The Organization of Petroleum Exporting Countries (OPEC), formed in the 1970s, exemplifies this approach, with Middle Eastern countries responsible for about two-thirds of the world's oil production agreeing to coordinate production levels and prices. This cooperative behavior essentially transforms multiple firms into a shared monopoly, maximizing collective profits through coordinated action rather than competitive rivalry.

In collusive oligopoly, firms form cartels to coordinate pricing and output decisions, acting like a monopoly. A cartel is an agreement among competing firms to limit production and raise prices. The best example is OPEC (Organization of Petroleum Exporting Countries), where oil-producing nations coordinate to control global oil prices. Cartels are unstable because individual members have incentives to cheat on agreements.

In oligopolistic markets, prices tend to be rigid and resistant to change, particularly downward (price rigidity). Because companies don't want to start price wars, they instead compete through non-price means such as advertising, product design, and brand image. This is why industries like automobiles, beer, and consumer goods have extensive advertising campaigns.

When price competition is limited (as in oligopoly), firms compete through non-price factors: advertising, product differentiation, quality improvements, loyalty programs, and after-sales service. This explains why major retailers offer similar products at similar prices but compete on other dimensions.

Non-price competition refers to strategies used by firms to compete without changing the price of their product. This includes advertising, product differentiation, quality improvement, and other marketing efforts to attract customers.

Because imperfect competitors sell differentiated products, non-price competition becomes necessary. Non-price competition involves distinguishing products through unique attributes using commercials, labeling, and other marketing strategies to promote product superiority. Examples include TV commercials comparing trucks, detergent labeling highlighting stain-removing ingredients, and distinctive bottle shapes like Coca-Cola's recognizable design.

Non-price competition is essential in monopolistic competition because price wars would be destructive. Firms compete through advertising, celebrity endorsements, and product differentiation. Advertising serves to persuade buyers and differentiate products in competitive markets. In perfect competition, advertising is unnecessary because buyers and sellers already have perfect knowledge.

Three major oligopoly models explain firm behavior. The Bertrand model assumes competitors keep prices constant while firms adjust their own prices. The Cournot model assumes competitors keep output constant while firms adjust their own output. The Stackelberg model introduces a leader-follower structure where one firm (leader) chooses output first, and followers observe and respond. The leader typically produces more than followers due to first-mover advantage. These models differ in their assumptions about competitor reactions to price and output changes.

This section provides detailed analysis of three major oligopoly models. Cournot model: firms compete by choosing output quantities simultaneously, assuming competitor's output is fixed. Equilibrium output is n/(n+1) of perfect competition level, with price between monopoly and perfect competition. Individual firm output is 1/(n+1) of total. Bertrand model: firms compete by setting prices, assuming competitor's price is fixed. With homogeneous products and zero MC, equilibrium is P=MC (perfect competition outcome). With differentiated products, equilibrium price equals average cost. Stackelberg model: one leader moves first and knows follower's reaction function, incorporating it into profit maximization. Leader produces more than Cournot, earns higher profits. Comparison: Cournot (quantity competition, downward sloping reaction curves), Bertrand (price competition, upward sloping reaction curves), Stackelberg (leader-follower, first-mover advantage).

The three major oligopoly models are Cournot, Bertrand, and Stackelberg. In the Cournot model, both firms simultaneously determine their output quantities, assuming the competitor's output remains constant. In the Bertrand model, both firms simultaneously determine their prices, assuming the competitor's price remains constant. In the Stackelberg model, one firm (the leader) moves first and sets its output, while the second firm (the follower) observes this decision and then sets its own output. The leader has first-mover advantage and can anticipate the follower's reaction. The follower is assumed to be naive and does not learn from past mistakes. The leader knows how the follower will react and incorporates this into its decision. The leader will produce more output than in the Cournot model, while the follower will produce less. The leader earns higher profits while the follower earns lower profits compared to the Cournot equilibrium.

This video explains three fundamental oligopoly competition models: (1) Bertrand competition, where firms simultaneously set prices and end up producing at marginal costs (same as perfect competition); (2) Cournot competition, where firms simultaneously choose quantities, producing more than monopoly quantity but less than perfect competition; and (3) Stackelberg competition, where one firm moves first (leader) and captures more market share, producing more than Cournot but less than monopoly quantity, with the second firm (follower) producing less than Cournot equilibrium.

Oligopoly models explain firm behavior: (1) Cournot model - firms compete on quantity, each assuming rival's output is fixed, leading to 1/3 market share each with two firms, (2) Bertrand model - firms compete on price, driving prices to MC even with two firms, (3) Stackelberg model - leader-follower structure where leader sets output first, earning higher profits, (4) Sweezy kinked demand model - explains price rigidity through asymmetric rival responses to price changes.

Paul Sweezy's kinked demand curve model (1939) explains oligopoly price rigidity. The model assumes that if a firm raises prices, competitors won't follow (elastic demand), but if a firm lowers prices, competitors will match (inelastic demand). This creates a kink in the demand curve at the current price, explaining why oligopolistic prices tend to remain stable even when costs change. Criticisms include: unrealistic assumption that competitors' output remains constant, zero production cost assumption is unrealistic, failure to account for adjustment periods, and assumption of perfect knowledge. Despite limitations, it provides a useful framework for understanding oligopoly behavior.

The kinked demand curve model explains price rigidity in oligopoly. The model assumes: (1) If a firm raises prices, competitors will not follow, causing the firm to lose significant market share, (2) If a firm lowers prices, competitors will match the price reduction to maintain market share, (3) This creates a kink in the demand curve at the current price, (4) The marginal revenue curve has a gap at this point, making price changes unprofitable.

In oligopoly markets with pricing interdependence, firms face a kinked demand curve based on asymmetric competitor responses. Competitors ignore price increases but match price decreases, creating distinct elasticities on either side of the kink. When a firm raises prices, competitors maintain theirs, causing significant demand loss (high elasticity). When a firm lowers prices, competitors follow suit, reducing substitution effects (lower elasticity). This results in a discontinuous marginal revenue curve. The model explains stable prices but does not explain how equilibrium prices are determined.

The kinked demand curve theory, developed by Paul Sweezy from Harvard in the 1950s, explains price rigidity in oligopolistic markets by showing that firms face an elastic demand curve above the equilibrium price (causing customer loss if prices rise) and an inelastic demand curve below it (causing no customer gain if prices fall), creating a kink that makes firms reluctant to change prices even when costs change, as the marginal revenue curve becomes effectively vertical at the equilibrium point.

The kinked demand curve, developed by American economist Paul Sweezy, is a model used to explain price rigidity in oligopoly markets, where the demand curve is divided into two segments: the segment above the market price is highly elastic (consumers easily switch to competitors if one firm raises prices), while the segment below the market price is inelastic (competitors also reduce prices, limiting demand increases for the firm that initially lowered its price).