Maureen Miskovic left the bank abruptly yesterday, 11 weeks after she was embarrassed by the discovery of $2bn (£1.27bn) of “rogue” trades.
Ermotti, who was confirmed as chief executive little more than two weeks ago, has replaced her with Americas head Philip Lofts, a veteran of more than 20 years at UBS who now returns to his previous role.
There were also promotions for Americas wealth management chief Bob McCann and chief operating officer Ulrich Koerner, who had both been rivals to Ermotti for the top job.
Both men will keep their current responsibilities but McCann will also become Americas chief executive and Koerner will also take control of Europe, the Middle East and Africa.
“One of my main priorities is to continue to reinforce the bank’s risk framework,” Ermotti wrote in a memo to staff yesterday.
The reshuffle is the latest in a series of changes since the exposure of the “rogue” trading scandal, which triggered a split among senior executives and ultimately led to the resignation of chief executive Oswald Grübel.
UBS insists the departure of Miskovic – who joined from financial services group State Street – was unrelated to the losses allegedly racked up by Kweku Adoboli, who is on remand in Wandsworth jail.