China's benchmark stock index tumbles 5.4 percent on declines in PetroChina AP - 56 minutes ago SHANGHAI, China - China's benchmark stock index tumbled 5.4 percent Thursday to its lowest level in 11 months, dragged down by dramatic declines in PetroChina and other large cap stocks. The main Shanghai Composite Index fell 195.36 points to close at 3,411.49 points, its lowest finish since April 9. The benchmark index on the smaller Shenzhen exchange shed 4.2 percent to 1,161.66. PetroChina, China's biggest oil producer, led the declines, dropping 8.3 percent to 16.99 yuan, slightly above its IPO price of 16.70. PetroChina...