China's stock index futures closed lower Friday with the contract for August, the most actively traded, down 1.85 percent from the previous trading day to end at 2,911.6 points.

The September contract lost 2.09 percent to 2,921.8 points. The December contract went down 2.05 percent to 2,965.6 points, and the March 2011 contract dropped 2.10 percent to 2,998.2 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.