discriminatory pricing

discriminatory pricing　歧视定价　

It exists when sales of identical goods or services are transacted at different prices from the same provider.In a theoretical market with perfect information，perfect substitutes，and no transaction costs or prohibition on secondary exchange（or reselling）to prevent arbitrage，price discrimination can only be a feature of monopolistic and oligopolistic markets，where market power can be exercised.Otherwise，the moment the seller tries to sell the same good at different prices，the buyer at the lower price can arbitrage by selling to the consumer buying at the higher price but with a tiny discount.However，product heterogeneity，market frictions or high fixed costs（which make marginal-cost pricing unsustainable in the long run）can allow for some degree of differential pricing to different consumers，even in fully competitive retail or industrial markets.Price discrimination also occurs when the same price is charged to customers which have different supply costs.