Thursday 7 January 2016 6:40 am

How low can yuan go? Trading on the CSI 300, Shenzhen Composite and Shanghai Composite suspended after People's Bank of China's devalues renminbi

Trading on China's stock markets has been suspended for the second time this week, after China accelerated the depreciation of the renminbi, a move which rippled through regional currencies and domestic stock markets. 

The so-called circuit-breaker was triggered after just 870 seconds (that's just under 15 minutes) of trading, helping China's stock market clock the shortest trading day in its 25-year history.

The mechanism had been used for the first time ever on Monday, the first day of trading this year, to stem a sell-off sparked by mounting fears over the Chinese economy. Introduced in the wake of volatility this summer, it kicks in when the market falls by five per cent. 

Earlier today, the People's Bank of China shocked markets by setting the official midpoint rate of the renminbi at 6.5646 per dollar, its lowest level since March 2011.

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That was 0.5 per cent weaker than the day before and the biggest daily drop since last August, when an abrupt, near-two per cent devaluation of the currency also riled markets.

This sent China's blue-chip CSI 300 index down 7.21 per cent at 3,284.74 points. Meanwhile, the Shanghai Composite Index shed 7.32 per cent at 3,115.89 points, while the Shenzhen Composite Index was 8.24 per cent lower at 1,958.09 points.

ANZ Bank said in a note: "The policy action will also create one-way expectation of RMB depreciation, propelling capital flight and leading to significant financial instability."