Aggregation with Cournot competition : the Le Chatelier Samuelson principle

This paper studies the aggregate substitution and expansion effects triggered by changes in input prices in a context where firms supply a homogeneous commodity and compete in quantities à la Cournot. We derive a sufficient condition for the existence of a Cournot equilibrium and show that this condition also ensures that the Le Chatelier-Samuelson principle is satisfied in the aggregate at the Cournot equilibrium, although it may not be satisfied at the firm level.