That might sound odd given Beijing deliberately devalued its currency in August, but it's another example of Chinese policy makers failing to anticipate the market's reaction and paying the price. 

New official figures show China's foreign-exchange reserves fell by a staggering $99.5 billion last month as Beijing sold US dollars and bought yuan to stem its fall against major currencies. That's more than oil-rich Oman's economy is worth, according to the World Bank.

China's central bank still boasts the world's largest stockpile of foreign currency — worth $3.23 trillion — but it's hit the lowest level since May 2012. January's drop-off followed a record fall of $107.9 billion in December.