Last week, the equivalent of 41 million bales of cotton traded in a single day on the Zhengzhou Commodity Exchange, the most in more than five years and enough to make almost 9 billion pairs of jeans, or at least one for every person on the planet. Prices that had slumped to the lowest on record in February surged almost 19 per cent in the four days leading up to the trading spike recently.

Meanwhile, traders have piled into Chinese commodity markets, sending volumes of everything from steel to coking coal soaring and prompting exchanges to boost margins and fees or issue warnings to investors. The surge in trading is reminiscent of last year’s equities rally that boosted the stock market before a rout erased $5 trillion. China is the world’s largest consumer of cotton and second-biggest producer.

More than 3.6 million contracts of 5 tonnes apiece traded in Zhengzhou on a single day. With Chinese exchanges double counting volume to account for the long and short side of a trade, that’s still about 9 million tonnes, or 41 million bales. One bale can make 215 pairs of jeans, according to the National Cotton Council of America.

On the same day, about 1.6 billion pounds traded on ICE Futures in New York. That’s about 3.3 million bales, or more than 700 million pairs of jeans, enough to dress up the US, Brazil and Japan in denim.