Uh-oh. While investors have been distracted by the brightly coloured balloons of rebounding economic output, the Baltic Dry Index, a measure of shipping costs for commodities, has been quietly deflating. Daily rates for leasing the largest Capesize vessels are down about a quarter over the past fortnight. Since nudging over 4,000 in early June, the BDI – a composite of rates for four sizes of ship – has fallen 44 per cent.

As a gauge of demand for materials used in the early stages of production – such as iron ore, coal and grain – the BDI should, in theory, be an effective leading indicator for the world economy. The problem is distortions on the supply side, such as port congestion and the vagaries of the two- or three-year cycle from order to delivery of new ships. Excess capacity is about to warp the picture once more: 128 Capesizes are due to be delivered by the end of this year, equivalent to 14 per cent of the existing fleet.