DEGREASING THE WHEELS OF FINANCE
构建动态一般均衡模型，研究个体面临流动性冲击时，金融市场过度交易是否可能。发现最优政策是限制市场准入，因为资产组合选择存在货币外部性。
Can there be too much trading in financial markets? We construct a dynamic general equilibrium model, where agents face idiosyncratic liquidity shocks. A financial market allows agents to adjust their portfolio of liquid and illiquid assets in response to these shocks. The optimal policy is to restrict access to this market because portfolio choices exhibit a pecuniary externality: Agents do not take into account that by holding more of the liquid asset, they not only acquire additional insurance against these liquidity shocks, but also marginally increase the value of the liquid asset, which improves insurance for other market participants.