UBS has tapped Asian and Middle East investors for Sfr13bn (€7.9bn) in convertible bonds to shore up its balance sheet and support its wealth management business after revealing a further $10bn (€6.8bn) in writedowns related to the US sub-prime crisis.

In total, the Swiss banking group said it has added Sfr19.4bn (€11.7bn) to its tier one capital. It warned today the further writedowns will push it into the red in the fourth quarter and also possibly for the full financial year. The announcement comes less than two months after UBS said it expected to return to the black at group level in the fourth quarter, even though its investment bank was unlikely to contribute to profits.