A stable aggregate currency revisited: Highlighting some fundamental issues
指出稳定综合货币（一种通过最小方差投资组合优化得到的最优多货币计价单位）概念存在基本问题，一旦解决这些问题，优化问题将不可行。适合对货币篮子设计或汇率指数感兴趣的学者。
A multicurrency numéraire is a weighted basket of currencies, where the weights sum to zero and all weights are positive. A stable aggregate currency is an optimal multicurrency numéraire, which is estimated using a minimum-variance portfolio optimisation. The variables of the portfolio optimisation are invariant currency indexes, which are multilateral exchange rates and are priced in terms of an equally-weighted basket of the currencies. This paper shows that there are some fundamental issues with the concept of a stable aggregate currency. Once these issues have been resolved, it is shown that the portfolio optimisation problem is infeasible.