Green beans and trillions of yuan

In Liu Guoda's shop, there are many types of grain. If you look carefully, you can spot a sack of green beans sitting quietly among the more popular varieties of rice, corn and peanuts.

Few people buy the beans, of which China grows just one million tonnes a year, compared with 200 million tonnes of rice and 130 million tonnes of corn. But it is the humble bean that keeps alive Zhengzhou's futures market, the biggest on the mainland, with a turnover last year of two trillion yuan (about HK$1.87 trillion), of which green beans accounted for 80 to 90 per cent.

It should not be so. China is the world's biggest producer of farm goods and the green bean is one of the least important. But the story of how the futures market has come to depend on it reflects the short and turbulent history of futures trading in China and how the market has become increasingly divorced from the reality of the world outside the trading floor.

Zhengzhou's futures market could be in Central or Manhattan. It is housed in the city's fanciest building, a grey concrete and glass skyscraper completed in May 1997 at a cost of 650 million yuan, with a 22-storey office building, four-star hotel and apartment block for the brokers.

Trading is on the seventh floor, with seats for 460 brokers in front of a giant electronic board posting present and future prices for the beans. About 200 brokers are trading, in red jackets, in front of their computers.

In front of the Future Building, as it is called, black limousines disgorge men in pin-striped suits clutching mobile telephones on which they discuss the latest prices or where to have dinner.