China's stock index futures open lower Tuesday with two of the four contracts down at the opening from the previous trading day.

The contract for May, which is most actively traded, fell 18.4 points to open at 3,201.2. The June contract dropped 17.2 points to open at 3,237.8. The September contract opened at 3,312.0, unchanged from previous trading day, and the December contract also opened flat at 3,390.4 points.

The stock-index contracts, agreements to buy or sell the Hushen 300 Index at a preset 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.