China's stock index futures were mixed at their openings Tuesday with the contract for settlement in August, the most actively traded, adding 1.6 points, to open at 2,928 from the previous trading.

The September contract opened at 2,944, up 4 points from the previous trading while the December contract opened at 2,985.4, up 3.2 point from the previous trading.

The contract for settlement in March 2011 climbed 4.2 points to open at 3,020.2.

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.