The benchmark Shanghai Composite shed 4.2% at the opening bell, only to recover and lurch into positive territory by mid-day. The smaller Shenzhen Composite followed a similar pattern, opening nearly 5% lower before mounting a recovery.
The Shanghai index has now crashed roughly 40% from its June 12 peak, leaving the index with a 3% loss since January.
Beijing has acted aggressively in recent months to prop up stocks. The central bank has injected cash into the financial system and state-backed brokerages have been ordered to buy stocks, but the measures have largely failed to stem losses.
