Export taxes in Nash equilibrium boost welfare over free trade in duopoly.
Export taxes in a Bertrand duopoly lead to higher welfare in the Nash equilibrium compared to free trade, as shown in the Eaton and Grossman (1986) model.
Free Trade Boosts Welfare Under Duopoly with Differentiated Products
Price competition boosts consumer welfare in oligopolies, study finds.
International trade may harm welfare in oligopolies with similar products.