Chinese investors in Hong Kong and on the mainland have long used water as the vivid metaphor to describe liquidity sloshing in the financial system.
No sooner had financial pundits and newspaper headlines begun to warn about 'brimming water' than the US Federal Reserve opened another sluice gate earlier this month by deciding to pump an additional US$600 billion into its economy in the second around of quantitative easing.
It is little wonder that senior mainland officials and economists have joined the growing international chorus of criticising Washington's latest programme, which could accelerate capital inflows into developing nations and lead to higher inflation.
Beijing has genuine concerns that the mainland would be the top destination for the hot money as overseas investors seek to cash in on its strong growth and the potential upside of further yuan appreciation.
It is difficult to estimate the size of speculative capital flowing into the mainland as the bulk was invested through illegal channels because of China's tight capital controls. But one can safely assume that it's billions of US dollars each month. One crude measure is to find the unexplained amount of money in the monthly or quarterly additions in foreign exchange reserves after accounting for the trade surplus and foreign direct investment and currency fluctuations.
But the 'water' seldom flows one way. In fact, the mainland is also surely but quietly witnessing massive outflows of capital, most of which flow into the developed countries and regions, US and Hong Kong among the top destinations.
