Kweku Adoboli has pleaded not guilty to two counts of fraud and two counts of false accounting between 2008 and 2011.
Ghana-born Adoboli was a senior equities trader with the bank in London when he was arrested in September 2011 after UBS discovered irregularities in trading records. The bank estimated its loss at $2.3 billion.
The incident hurt the bank's efforts to restore its image after a Swiss government bailout and a tax evasion investigation in the United States.
Prosecutors are expected to begin laying out their case against 32-year-old Adoboli at London's Southwark Crown Court on Friday. The trial is scheduled to last eight weeks.