Even by their usual standards of unpredictability, asset markets have had a funny 12 months. Since the credit squeeze began shares have fallen and then rallied, fallen and then rallied, even as economic shocks have rocked the world. But now the cracks are showing. Asset price falls this week suggest that the chance of a global economic slowdown has risen.

US and European stock markets have had a bad week and so have indices that measure the risk of corporations defaulting on their debt. There were several striking items of corporate news: not least a dramatic fall in sales at UK retailer Marks and Spencer, a bell-wether stock.