Vimal Gor, head of income and fixed interest at BT Investment Management, argued that trying to assert control over money fleeing an economy's borders can be a bit like preventing a run on a bank.

"The market sees capital outflows and devaluation more akin to what a failing bank looks like in its final days – a bank run precipitating a falling stock price, which encourages further doubt and so on," the fund manager says in his widely followed investor newsletter.

"The capital outflows are the depositor withdrawals and the exchange rate is the stock price. This is because similar issues around opacity affect banks as well. When a bank run is occurring, as Mervyn King, ex-governor of the [Bank of England] once said, it is rational to participate in it."

Part of China's problem is that its capital controls have proved incredibly porous and money is still leaving the country despite restrictions imposed by financial institutions. The depreciation of the yuan, which began in earnest in August 2015, has not deterred wealthy Chinese from trying to move their cash abroad.

"For those in power, moving this money overseas is the rational thing to do, and should be independent of whatever the exchange rate is," Mr Gor said. "This means that FX reserve depletion could well be the actual trigger for a hard landing in China, rather than a collapse of the banking system, which is still clearly under the party's control.