Shanghai stocks plunge more than 4% at open

Shanghai stocks tumbled more than four percent at the open Wednesday after racking up big gains a day earlier after a week-long break, but Hong Kong clawed back some of the losses of more than nine percent it suffered.

The Shanghai Composite Index shed 4.54 percent, or 158.45 points, at 3,331.33, and the Shenzhen Composite Index on China's second exchange, dropped 4.31 percent, or 90.51 points, a