Do Mergers Increase Product Variety? Evidence from Radio Broadcasting
利用1996年电信法提供的自然实验，研究并购对广播电台节目格式多样性的影响，发现市场集中度提高反而增加了绝对多样性，机制是空间预占减少了产品拥挤。
Mergers can reduce costs and alter incentives about how to position products, so that theory alone cannot predict whether mergers will increase product variety. We document the effect of mergers on variety by exploiting the natural experiment provided by the 1996 Telecommunications Act. We find that consolidation reduced station entry and increased the number of formats available relative to the number of stations. We find some evidence that increased concentration increases variety absolutely. Based on the programming overlap of jointly owned stations, we can infer that the effects operate through product crowding that is consistent with spatial preemption.