We study how market segmentation affects consumers when a monopolist can adjust both prices and product qualities across segments, engaging in second- and third-degree price discrimination simultaneously. We characterize the consumer-optimal segmentation and show that it has a striking structure: consumers with the same value receive the same quality in every segment, though prices differ. Under mild conditions, any segmentation harms consumers if and only if demand is more elastic than a cost-determined threshold. Hence, potential benefits for consumers depend critically on cost and demand elasticities. These findings have implications for regulatory policy regarding price discrimination and market segmentation.

翻译：我们研究当垄断者能够同时调整不同细分市场的价格和产品质量，并实施二级和三级价格歧视时，市场分割如何影响消费者。我们刻画了消费者最优分割的特征，并表明其具有显著的结构：相同支付意愿的消费者在每个细分市场中获得相同的产品质量，尽管价格存在差异。在温和条件下，当且仅当需求弹性超过成本决定的阈值时，任何形式的市场分割都会损害消费者利益。因此，消费者可能获得的收益关键取决于成本与需求弹性。这些发现对价格歧视与市场分割的监管政策具有重要启示。