The big banks’ raid on the coffers of sovereign wealth funds and other institutional moneybags is uncannily reminiscent of the capital raising that took place after the dot.com bubble. Then it was the telecom companies that were busily shoring up balance sheets. And the lessons of history for those coming to the rescue of banks today are far from reassuring.

Telecoms companies were big borrowers in a high-tech bubble that was otherwise largely financed by equity. All across Europe they over-invested in new capacity, over-paid for acquisitions and over-paid for third generation mobile phone licences. After the bust many found themselves on the brink of collapse. They avoided the worst by tapping investors for fresh equity.