In the rarefied world of bulk commodities, where traders deal in quirky products like pork bellies, milk powder and gold, it can take years to change the way goods are bought and sold. Tradition is important in a market that has its roots in the early 1800s, and innovation doesn't happen overnight. Yet, earlier this year, the world's three largest producers of iron ore and coking coal succeeded in their plot to dump a decades-old annual contract-pricing system in favour of a quarterly spot market. The switch was achieved in a matter of months and there is already talk of daily spot trading on the horizon.
In theory, spot markets...