The value of a UBS real estate fund once valued at $6bn (€4.4bn) and now being dissolved by the Swiss bank dropped sharply from the end of the year, with the net asset value 20% lower, according to a document seen by Dow Jones Newswires.

The drop is in part due to a further fall in property values but also because of costs including those linked to future disposals and taxes, according to the document, prepared for UBS' private bankers to discuss with their wealthy clients.