Ex-UBS boss Luqman Arnold said the bank should be broken up, after being hard hit by the credit crunch.
Arnold says UBS needs a shake-up in its corporate governance procedures and should sell its asset management unit along with other units and separate its investment and private banking businesses.
Those other units, which Arnold thinks should be sold include its Brazilian and Australian subsidiaries. Combined with the sale of the asset management division this could raise $15 billion, he says.
However, UBS defends the strategy of combining the private and investment banking businesses and is yet to publicly respond to Arnold's letter.