System upgrade causes stock market upset

Shanghai Stock Exchange said a system upgrade caused some cross-market indexes to malfunction on Monday morning but normal service had been resumed by 1pm.

The indexes erroneous intraday highs and lows will be corrected after Monday’s close, the Shanghai Stock Exchange said.

Some cross-market indexes such as CSI 1000, CSI 300  and health-care shares showed abnormalities during the morning. 

Prices showed the CSI 300 Health Care Index falling as much as 17 percent at the opening, even though none of the 29 stocks in the industry group lost more than 2 percent. 

The CSI 300 index added 0.4 percent at close, after dropping more than 2.3 percent in the morning session. The CSI 1000 Index rose 1.6 percent after an earlier surge of as much as 6.6 percent. 

After discovering the situation, the Shanghai Stock Exchange launched an emergency response plan and an investigation together with China Securities Index Co Ltd.

The investigation found that the incident was caused by a weekend upgrade of the cross-market index-calculation system.