West Texas Intermediate crude fell to $75 per barrel, down 49.5 per cent in three months. Brent crude touched $70 per barrel, down 52.6 per cent. The trade from which many hedge funds profited in the first year of the credit crisis of going long oil, while shorting banks, would have lost 56.6 per cent in the past three months (assuming banks are represented by the KBW index of US commercial banks).

Over this period, the S&P financials index is down only 4.5 per cent, but energy stocks are down 38.3 per cent. Materials are down almost as much.

The oil price fall triggered the problems for hedge funds, which finally spilled over into forced sales of equities. A new fear is that debts taken by companies hoping to profit from high oil prices could run into trouble.