Third, the foreign-exchange channel of QE transmission – the currency weakening implied by monetary easing – is ineffective if several major central banks pursue QE at the same time. When that happens, QE becomes a zero-sum game, because not all currencies can fall, and not all trade balances can improve, simultaneously.
第三，如果主要国家央行同时实施QE的话，QE传导的外汇渠道——货币宽松隐含的汇率走软——也会变得无效。那将会导致一场零和博弈，因为所有的币种同时走软，各国的贸易收支表同时达到平衡，是不可能的。结果就是作为“汇率战争”代名词的“QE战争”。