Chinese stocks nosedived on Monday, with the benchmark Shanghai Composite Index down 8.45 percent to close at 3,211.2 points by midday.
The Shenzhen Component Index lost 7.27 percent to close at 10,983.42 points, Xinhua news agency reported.
The ChiNext Index, tracking China's NASDAQ-style board of growth enterprises, fell 8.05 percent to close at 2,153.52 points.
Shares in all sectors tumbled more than eight percent. The banking and mining industries lost the least, but still dropped more than 8.3 percent.
The slump came despite the government's decision on Sunday to allow pension funds to invest in the stock market.