There are ripples of worry spreading among commodities traders and fund managers.
This year’s bull-run in oil and metals is still underway, with futures contracts for the 20 most-traded US commodities up 6.6pc in the third quarter. The market is on its steepest rise since the first quarter of 2008. Investors have poured $10.2 billion into commodity funds this year, a six-fold increase from 2008, according to EPFR Global.
There’s been a big rebound this year in oil (up 57pc) and especially copper (up 90pc).
At the same time, however, it’s clear that the world has not recovered from the financial crisis, and plenty of indicators suggest that the bulls may have got ahead of themselves. The Baltic Dry Index, which shows us the price of shipping, took a 41pc tumble in the third quarter as demand for freighters dried up.
And big commodities companies, such as Alcoa, the US aluminium firm, are losing money, according to analysts. The IMF is wondering whether the surge in commodities is a "short boom".
In the copper market, all eyes are on China. There is talk that China has amassed an enormous stockpile of the metal, and may soon stop buying.
Monthly shipments to China fell by a quarter in August and a poll of analysts by Bloomberg suggested that copper prices may dip 22pc this quarter, compared to last year.
Antaike, a local metals consultancy, thinks China has a stockpile of 1.2 megatonnes of refined copper, equivalent to six months of supply.
However, this is likely to be an exaggeration, deduced by taking into account a low level of use, the maximum level of imports, and barely any substitution of refined copper for scrap.
In fact, consumers have probably swapped around 400 kilotonnes of refined copper for scrap, according to Barclays Capital, and they estimate that the stockpile is no greater than 400 to 500 kilotonnes.
More importantly, it seems unlikely that China will stop buying copper anytime soon. The country’s demand for the metal has doubled in the past six years, but the weakness of local metals exchanges means that it has to keep a large supply on hand in order to smooth out any gaps in the pipeline.
With construction funded by the stimulus plan still in full flow, copper shipments will keep rising.