China stocks bounced sharply for the second day on Friday, reversing an early-week slump in frenetic trading as markets regained a measure of composure following a barrage of government support steps to stem the rout. The CSI300 index of the largest listed companies in Shanghai and Shenzhen rose 5.4 percent, to 4,106.56, while the Shanghai Composite Index gained 4.6 percent, to 3,877.80 points.