As anyone who has received an astronomical hotel phone bill will know, it helps to know costs in advance. This applies to manufacturers as well, who tend to like reliable delivery of materials at preset prices. But agreeing to supply such contracts may reflect a lack of market power. If you can pass higher costs straight on to customers, why tie yourself down?

Such a thought may be going through the minds of steelmakers. Spot prices for the metal have leapt this year in response to the dramatic increase in prices for coking coal and iron ore – the two main ingredients of steel. The cost to produce a tonne of steel has risen by about $200, or almost half.