The watchdog, which in August dropped proceedings against four other UBS foreign exchange traders, is still considering action against one other individual.
UBS is one of the seven European and U.S. banks to have been fined over currency market rigging after U.S. and UK authorities described how traders gathered in chatrooms with names such as "The Cartel" and "The Mafia" to share confidential client information and coordinate trades to boost their own profits between 2008 and 2013.
UBS paid $545 million in May to settle regulatory investigations into both currency and interest rate manipulation.
Regulatory investigations into individuals elsewhere continue. In Britain, criminal proceedings take precedence over civil action.
To date, there has been one British arrest. Paul Nash, a former Royal Bank of Scotland (RBS.L) foreign exchange trader, was arrested at the end of last year shortly before he planned to emigrate to Canada. He has not been charged.
