BEIJING -- China's stock index futures closed mixed on Friday with the contract for August, the most actively traded, down 0.03 percent from the previous day to 3,075 points.

The September contract closed up 0.03 percent to 3,088.2 points. The December contract gained 0.06 percent to 3,133, while the March contract for 2012 was up 0.16 percent, to 3,183 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.