Analysts today claimed the worst of UBS' sub-prime balance sheet problems are now over after it announced a bigger than expected Sfr12.5bn (€7.8bn) net fourth-quarter loss, but they warned of fresh concerns about the Swiss bank.

Shares in UBS fell by as much as 4% to Sfr44.9 in early trading before recovering to Sfr46.4 by 09:25 GMT, less than 1% below yesterday’s Sfr46.8 closing level, after the Swiss bank warned its US sub-prime losses in the fourth quarter increased from the $10bn writedown indicated on December 10 to $12bn in the final three weeks last year.