This figure is in addition to the $18.4 billion it wrote off during 2007 and means that losses from US real estate and associated credit agreements now total $37 billion (Â£18.5 billion.)
Consequently, the bank also said that it expects 2008 first quarter net losses to total Â£12.1 billion.
It was announced that chairman Marcel Osper will not seek re-election, and the bank will create a business devoted to the now worthless US property assets.
The bank said that it has "substantially reduced its real estate related positions through both valuations adjustments and significant disposals".
"UBS is confident that these measures will deal effectively with the firm's real estate exposures and allow the bank to focus on strengthening its core operations," it said in a statement.
Marcel Rohner, UBS chief executive, explained that the bank had now "created the basis to weather one of the most difficult periods in the history of the industry".