China's benchmark Shanghai stock index closed down 5.90 percent on Wednesday, as new government policies aimed at averting a market slide failed to have an impact, dealers said.

The Shanghai Composite Index slumped 219.93 points to 3,507.19 on turnover of 700.2 billion yuan ($114.5 billion). The Shanghai index fell as much as 8.20 percent during the day.

The Shenzhen Composite Index, which tracks stocks on China’s second exchange, lost 2.50 percent, or 48.38 points, to 1,884.45 on turnover of 414.2 billion yuan. It fell as much as 4.20 percent.