Optimal Financial Transaction Taxes
在一个金融市场均衡模型中，如果投资者持有与基本交易动机无关的异质信念，且计划者用任一单一信念计算福利，则正交易税是最优的；最优税可通过调整至总交易量等于基本交易量来实现。
ABSTRACT This paper characterizes the optimal transaction tax in an equilibrium model of financial markets. If investors hold heterogeneous beliefs unrelated to their fundamental trading motives and the planner calculates welfare using any single belief, a positive tax is optimal, regardless of the magnitude of fundamental trading. Under some conditions, the optimal tax is independent of the planner's belief. The optimal tax can be implemented by adjusting its value until total volume equals fundamental volume. Knowledge of (i) the share of nonfundamental trading volume and (ii) the semielasticity of trading volume to tax changes is sufficient to quantify the optimal tax.