Multiproduct mergers and quality competition
研究了质量差异关键的市场中企业合并的影响，发现无协同效应的合并可能通过产品组合效应提高消费者剩余，但仅当合并前行业结构满足特定条件时；合并后协同效应可能降低消费者剩余，且赫芬达尔指数变化可能误导对消费者影响的判断。
Abstract We investigate mergers in markets where quality differences between products are central and firms may reposition their product lines by adding or removing products of different qualities following a merger. Such mergers are materially different from those studied in the existing literature. Mergers without synergies may exhibit a product‐mix effect which raises consumer surplus, but only when the pre‐merger industry structure satisfies certain observable features. Post‐merger synergies may lower consumer surplus. The level of, and changes in, the Herfindahl–Hirschman Index may give a misleading assessment of how a merger affects consumers. A merger may benefit some outsiders but harm others.