UBS, Switzerland's biggest bank, has ejected its British president, Luqman Arnold, after less than a year in the job.

In his place, it has chosen the group's ex-finance director and head of UBS Asset Management, Peter Wuffli, who is a Swiss national.

"The change represents a number of differences of opinion," the bank said in a statement. "There are no financial, operational or control issues behind it."

That was not enough for investors, and UBS's share price sank nearly 5% with dealers seeing the move as evidence that the company was backtracking on reform.

In any case, sudden departures such as this are assumed to show discord within an organisation.