LONDON — UBS AG remains committed to its U.S. brokerage business, Chairman Kaspar Villiger and Acting Chief Executive Sergio Ermotti told staff, according to an internal memo seen by Dow Jones Newswires on Monday.

"Wealth Management at UBS has a global footprint and is a core pillar of the firm's integrated business model," Villiger and Ermotti said.

"Again, this business is not sale," the memo added.

The memo follows another one circulated to UBS staff over the weekend, assuring them that the bank was confident that it can realign to deal with the new market environment facing the financial services industry despite the "enormous challenges" it expects to face in the coming months.

On Saturday, the board accepted the resignation of CEO Oswald Gruebel in the wake of the Swiss bank suffering $2.3 billion in trading losses, allegedly caused by a London-based trader at UBS' investment-banking unit.

The bank's board appointed Ermotti, head of its European business, as interim CEO effective immediately. A search is under way for a permanent chief executive, with the board considering both internal and external candidates, Villiger told a conference call Saturday.

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