Economic policy uncertainty is a key determinant of exchange rate stability. This study investigates the impact of China's categorical economic policy uncertainties on the long-term correlation between onshore (CNY) and offshore (CNH) Renminbi (RMB) exchange rates. We find that fiscal policy uncertainty (FPU), monetary policy uncertainty (MPU), and exchange rate and capital account uncertainty (EXRPU) have a significant negative effect on this correlation, while trade policy uncertainty (TPU) has no significant impact. Furthermore, CNY and CNH do not effectively diversify risks and provide only limited hedging benefits.

Since September 1, 2014, the renminbi (RMB) offshore market in Taiwan has been started on according a cross-strait MOU. A completed RMB market in the Chinese Economic Area therefore has been established. Due to political and economic disruptions, such as the aftermath of the global tsunami, mainland China’s stock market crash and RMB exchange rate reform in 2015, as well as failure of the Service Trade Agreement between Taiwan and mainland China in 2016, the arbitrage opportunities among the three RMB markets can be explored. This paper evaluates the convergence and divergence of RMB market returns by the sigma-convergence (or log t) test, which provides a more precise indication for market return convergence than does the traditional unit root test. Policy implications for the RMB arbitrage are also provided.