Instability of Centralized Markets
集中市场虽能降低搜索成本、提高成交概率，但除特殊情况外，碎片化是其不可避免的特征，解释了证券和在线广告市场为何分裂为多个交易平台。
Centralized markets reduce search for buyers and sellers. Their “thickness” increases the chance of order execution at nearly competitive prices. In spite of the incentives to consolidate, some markets, securities markets and on‐line advertising being the most notable, are fragmented into multiple trading venues. We argue that fragmentation is an inevitable feature of any centralized market except in special circumstances.