China sheds a few basis points of economic growth and investors take $305bn of commodities bets off the table. Does the arithmetic stack up?

Industrialisation in the world’s third-largest economy has provided a huge boost to commodity prices in recent years. No wonder. From 2003-07, the country accounted for almost all the global incremental growth in demand for lead; 70 per cent for aluminium and 62 per cent for copper, according to Lehman Brothers.