Theorists are out in force to find reasons for the recent slump in Chinese equities: slowing industrial production, unrestrained inflation, tightened monetary policy. Among the best explanations, though, is simple investor apathy.

The mainland market has always been dominated by individual investors, who own the great majority of the 159m registered trading accounts. Yet the proportion of active accounts – those that made at least one trade in the past week – has steadily fallen, from an average 14 per cent in 2009 to 9.5 per cent so far this year. That growing indifference seems to have underpinned a longer-term trend. Only four of 90 main markets have done worse than Shanghai since the beginning of 2010 in local currency terms. The forward price/earnings ratio is now near a five-year low.

Restoring excitement will not be easy. If trendy companies such as Renren were to stay at home, perhaps, rather than list in New York, they might help to rebalance a market where the state-dominated finance and mining sectors account for almost all of the most-traded stocks. Listed companies might also disgorge more profits: among the 60 per cent of stocks that pay dividends, pay-out ratios average just 30 per cent. Boosting this, while essentially meaningless, would at least attract some attention. Perhaps the regulator could allow more foreign inflows, too. Overseas funds have been allocated a cumulative $19bn of A-shares since 2003, equivalent to less than 1 per cent of the current tradable market cap.