When all else fails, perhaps the oil price will come to the rescue. The eurozone crisis is hardly solved even though Spain’s banks have been bailed out. China’s growth rate is slowing. The US economy is treading water. Many banks still depend on central bank liquidity. But the oil price is at least retreating: Brent crude has fallen below $100 a barrel. The question is whether that is being driven merely by volatility or by actual assessments of risk.

The fall in the oil price is significant in that it has finally broken a notable trend. Brent crude traded above $100 a barrel for 240 days in a row, from October last year to May. That was its longest consecutive period ever above that price; when the oil price last spiked in 2008, it spent only 170 consecutive days above that level. Now it is back at about $97, and the short-term view is for more weakness.

Share prices of energy companies are tracking the retreat: the S&P energy index is trading broadly in line with the oil price. That makes sense: the fall will hit revenues and earnings per share, which tend to follow the oil price closely. The notable feature of oil companies’ numbers for 2011 and the first quarter of this year – that they were drowning in cash – should be a little less visible. That is true for both upstream and downstream operations. BP says that for every $1 movement in the oil price, its upstream pre-tax operating profit rises or falls by $300m. That is about 5 per cent of the $6.3bn pre-tax profit from its upstream business in the first quarter of 2012.