Ermotti said it was too soon to say whether clients had lost out as a result of UBS's behavior, which he described as "an industry issue."
"We are far from having an understanding of the effect of the actions of multiple institutions on the actual rate fixings, which one would need to know before trying to determine whether or how clients were affected," he said in a memo to staff.
UBS said Wednesday it expected to make a loss in the fourth quarter as a consequence of provisions for litigation and regulatory issues, but predicted pre-tax profit of $2.75-3.3 billion for the year.
Just last week, London-based lender HSBC agreed to pay $1.9 billion in a settlement with U.S. regulators over money laundering, a record for a case involving a bank.
UBS was fined nearly $50 million by British regulators last month after it failed to prevent a rogue trader from running up $2.3 billion in losses last year. In 2009, the bank paid $780 million as part of a deferred prosecution agreement in which it admitted to helping U.S. taxpayers hide money from the IRS.