China's stock index futures opened mixed Wednesday, with the contract for settlement in July, the most actively traded, opened at 2,558, down 6.6 points from the previous trading.

The contract expiring in August opened at 2,581, up 2.8 points from the previous trading.

The September contract opened at 2,596.8, up 0.8 points from the previous trading while the December contract opened at 2,652, up 3 points from the previous trading.

The stock-index contracts, agreements to buy or sell the Hushen 300 Index at a present value on an agreed date, are designed to allow investors to bet on and profit from both gains and declines in the market.

The index futures was launched at the China Financial Futures Exchange (CFFEX) and started trading from April 16, 2010. The CFFEX has set the base value for all the four contracts at 3,399 points.