Traders got a distraction from the wash of red on their screens Friday as China's share market served up a wild ride and a bit of a mystery.
The Shanghai Composite Index surged by as much as 5.6 percent in morning trade before ending down a tame 0.6 percent.
(Read more: China market bounce: trend change or false alarm?)
After the market close, major brokerage Everbright Securities offered itself as a key suspect, saying in a filing to the Shanghai Stock Exchange that its proprietary trading bureau encountered problems with its own arbitrage system, triggering talk the share spike may have been a result of a trading error.
Major Chinese business newspaper the 21st Century Business Herald reported Everbright was applying to cancel all its morning trades. China's market regulator said it was still probing the volatility late Friday afternoon.