'''''''''''''''' (Monetary Policy, Exchange Rate and Capital Flow From 'Equilateral Triangle' to 'Scalene Triangle')

Abstract

The English version of this paper can be found at http://ssrn.com/abstract=2949307. Chinese Abstract: 传统的“不可能三角”是一个“等边三角形”，但自2008年以来，资本流动的重要性提升，“等边三角形”向“不等边三角形”转化。我们首次提出了“不等边不可能三角形”，这是关于“不可能三角”更一般的分析框架。本文建立了理论模型，在“不等边不可能三角形”成立的前提下推导出不同汇率制度下针对跨境资本流动的最优宏观审慎管理水平和最优货币政策国际协调水平，并证明即使汇率自由浮动，中央银行也应对跨境资本流动实施一定的宏观审慎管理。基于本文模型和近年来的实践经验，我们提出了“宏观审慎管理加汇率灵活性加货币政策国际协调”的新宏观金融政策框架（New Macro-Financial Policy Framework, “New MFPF”），央行在三方面同时着力才能实现宏观总体平衡。 English Abstract: The traditional “Impossible Trinity” is an equilateral triangle. But since 2008, importance of capital flow has been greatly elevated, and equilateral triangle has transformed into scalene triangle. We first in the literature propose the “Scalene Impossible Trinity”, which is a more general analytical framework about “Impossible Trinity”. We also establish a theoretical model, and with the premise of “Scalene Impossible Trinity”, calculate the optimal level of macro-prudential management regarding cross-border capital flow and optimal level of international monetary policy coordination within different foreign exchange rate regimes. Our proof shows that even if foreign exchange rate could float freely, the central bank should conduct a certain level of macro-prudential management of cross-border capital flow. Based on this model and recent practices of The People’s Bank of China, we also present the New Macro-Financial Policy Framework (New MFPF), which is “Macro prudential management plus Exchange rate flexibility plus International monetary policy coordination.” Only by adopting this three-pronged strategy, the central bank could attain macroeconomic equilibrium.