Beijing, Aug 4 (IANS): Chinese stocks opened on a mixed note on Tuesday, with the benchmark Shanghai Composite Index down 0.03 percent at 3,621.86 points.

China issued new rules effective Tuesday to tighten short-selling activities in an attempt to stabilise the market, Xinhua reported.

Investors can not borrow shares and cover the short position on the same trading day, according to the Shanghai and Shenzhen stock exchanges statement.

Instead, investors must wait for the next trading day to pay back the shares they borrowed, adding to the uncertainty of the profits investors may lock in.

In short selling, speculators sell shares borrowed from lenders and buy back the stocks to cover the loan at a later time in the hope that share prices will fall during the period so they can earn the difference.

The Shenzhen Component Index opened 0.01 percent higher at 12,163.12 points on Tuesday.

The ChiNext Index, tracking China's NASDAQ-style board of growth enterprises, opened 0.12 percent lower at 2,396.41 points.