Shares nosedived with the benchmark Shanghai Composite Index plunging 8.5 percent, its worst single-day loss in eight years.

　　The smaller Shenzhen Component Index tumbled 7.6 percent. Nearly 2-thousand shares fell by the 10-percent daily limit.

　　Shortly after the closing bell, China's securities regulator urged its financial arm, China Securities Finance Corporation, to continue to buy stocks and stabilize the market.

　　Analysts struggled to explain the severity of the sell-off, which accelerated sharply in the afternoon session, long after investors had had time to digest the latest economic releases.

　　However, the 35-year-old investor Tan Minghui, who has experienced the recent market turmoil, is one of those who remains optimistic about the markets.

　　中国股市昨创8年来最大跌幅

　　"The market dropped a lot not too long ago, so now I have an immunity and am not especially anxious. I think the markets have reached their lows; there is not much space for further decrease, that's my personal opinion. I think it would rebound back after dropping."

　　Also on Monday, China's securities regulator said it has ordered investigations into another two companies for clues on margin lending activities through unofficial channels.

　　Following leads from the previous probe on Hangzhou-based financial software company Hundsun Technologies, the regulator has sent investigators to Shanghai Ming Chuang Techonology and Hithink RoyalFlush Information Network.

　　In early June, the Shanghai composite had risen by 152 percent compared to the previous July and nearly 60 percent since the beginning of the year.

　　But market conditions turned and, along with tightened regulation on margin trading, triggered a massive sell-off that saw the index plunge over 30 percent from its peak.

　　Although the government has stepped in with a string of stabilizing policies, market confidence seems hard to restore.

　　For more on the stock performance, CRI's Shane Bigham spoke with Gao Shang, analyst with Guantong Futures.