Comment: China new circuit breakers system
First, the new system-wide circuit breakers take effect when there is a 5 percent decline in the market (the benchmark CSI 300), which creates a 15-minute halt. If the market drops 7 percent, the market closes for the day. Hong Kong has no circuit breaker.
After hitting the limit of 5 percent and reopening after 15 minutes, it took roughly two minutes to hit down 7 percent, which triggered the final halt and closed the market.
Read more: http://www.cnbc.com/2016/01/04/chinas-new-circuit-breaker-may-have-worsened-drop.html