BEIJING - The ChiNext Index, tracking China's Nasdaq-style board of growth enterprises, tumbled 20.17 points, or 2.31 percent, to close at 854.71 points on Sept 19.

The index, together with the Shenzhen Component Index and the Shenzhen SME (small and medium-sized enterprises) Board Index, makes up the three core indices reflecting the performance of China's stocks listed on the Shenzhen Stock Exchange.

The ChiNext Board, which started trading on October 30, 2009, mainly lists high-tech companies and those with high growth potential.