Cournot competition is a foundational model of oligopoly developed by French mathematician Antoine Augustin Cournot in his 1838 work Recherches sur les principes mathématiques de la théorie des richesses. In the model, a small number of firms producing a homogeneous good simultaneously and independently choose how much to produce. The market-clearing price then adjusts based on total industry output via an inverse demand function.
Each firm chooses its quantity to maximize profit, taking rivals' quantities as given. The resulting equilibrium—a Cournot–Nash equilibrium—is the set of output choices where no firm can increase profit by unilaterally changing its quantity. With identical firms and constant marginal cost, the symmetric equilibrium yields output and price levels between those of perfect competition and pure monopoly. As the number of firms grows large, the Cournot outcome converges to the competitive outcome; with a single firm, it collapses to monopoly.
Key analytical features:
- Strategic substitutes: a rival's higher output lowers the residual demand each firm faces, so best-response functions are downward-sloping.
- Markup over marginal cost is inversely related to the elasticity of demand and the number of firms, captured in the Lerner index and linked to the Herfindahl–Hirschman Index (HHI) in symmetric equilibrium.
- Contrast with Bertrand competition (price-setting), which typically predicts marginal-cost pricing even with two firms, and with Stackelberg competition, where one firm moves first.
For policy researchers and MUN delegates working on competition policy, commodities, or OPEC-style coordination, the Cournot framework is the standard lens for analyzing capacity-constrained industries—crude oil, semiconductors, cement, steel, lithium—where output decisions are committed in advance and price adjusts. It also underpins empirical merger simulation tools used by competition authorities such as the U.S. Department of Justice, the European Commission's DG COMP, and the UK Competition and Markets Authority when evaluating concentration in producer markets.
Example
When OPEC+ members negotiated production quotas in 2023, analysts modeled the bloc's interaction with non-OPEC producers like the United States and Brazil as a Cournot-style quantity-setting game.
Frequently asked questions
Cournot firms compete by choosing quantities with price adjusting to clear the market, while Bertrand firms compete by setting prices directly. Bertrand typically predicts marginal-cost pricing with just two firms, whereas Cournot yields positive markups that shrink as the number of firms grows.
Keep learning