SHANGHAI'S key stock index dived nearly seven percent within 31 minutes of its opening this morning.

The Shanghai Composite Index, which tracks yuan-denominated A shares and hard-currency B shares, plunged 6.9 percent, or 337.46 points, to 4,576.98 at 10:01am. It opened at 4,818 at 9:30am.

Losers in the Shanghai market outnumbered winners 761 to 8 and 81 were unchanged at 10:24am. The index had recovered some ground, having lost 4.60 percent, or 226.27 points, to 4,688.17 at that time.