China's main share brokerages have agreed to spend 120 billion yuan ($19.3bn, £12bn) to prop up the ailing stock market.
The main Shanghai Composite index has fallen 30% since the middle of June, nullifying most of this year's gains.
The authorities are worried about the possible economic effects and have already tried preventative measures.
Twenty-one brokerages agreed the move at a meeting in Beijing on Saturday, Xinhua news agency said.
The brokerages "will jointly invest 15% of net assets as of the end of June, or no less than 120bn yuan, in blue chip exchange traded funds", the Securities Association of China said in a statement.