Systematic internalizers are single-dealer platforms run by investment firms that trade out of their own inventories by internalizing the trades off exchanges. We analyze the determinants of dealers' market shares and trading costs. We find that dealer trades have lower price impacts than exchange trades, consistent with uninformed traders seeking out dealers. Due to their ability to avoid trading with informed investors, dealers often undercut the exchange bid–ask spread when the spread is wide and the tick size is not binding. Dealers can therefore offer lower trading costs and gain a higher market share relative to exchanges.

中文翻译：

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与股票交易商交易的成本和收益：系统内部化者的案例

系统内部化者是由投资公司运营的单一交易商平台，这些平台通过将交易所的交易内部化来交易自己的库存。我们分析了经销商市场份额和交易成本的决定因素。我们发现经销商交易对价格的影响低于交易所交易，这与不知情的交易者寻找经销商的情况一致。由于他们有能力避免与知情投资者进行交易，交易商通常会在价差较大且报价单大小不具约束力时削弱交易所买卖价差。因此，交易商可以提供更低的交易成本，并获得相对于交易所更高的市场份额。