The comparative calm seen on China's stock market earlier on Thursday came to an abrupt end in the afternoon, with stocks tumbling into the close.
Having meandered around the flatline for most of the session, the benchmark Shanghai Composite tumbled in the final 30 minutes of trade, eventually ending the session down 2.20%.
The sudden drop in Shanghai hit trade in other mainland indices.
The SSE 50, comprising the largest listed firms by market capitalization in Shanghai, dropped by 2.55%.
Elsewhere, the CSI 300 and 500 indices, consisting of the 300 and 500 largest firms listed in Shanghai and Shenzhen, fell by 2.93% and 2.77% respectively.
As with most sudden movements in Chinese markets, there was no obvious catalyst to explain the sudden decline.
Given their recent track record, Chinese stock regulators will probably pin the decline on malicious short-selling initiated by mysterious foreign investors.
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