I characterize microfounded endogenous market structures with Bertrand and Cournot competition and perform welfare analysis generalizing the Mankiw-Whinston condition for excess entry. The impact of market leaders on welfare is reconsidered, with a number of policy implications about strategic...

We provide an extensive and general investigation of the effects on industryperformance - profits, social welfare and price-cost margins - of exogenously changing the number of firms in Cournot markets. This includes an in-depth exploration of the well-known trade-off between competition and...