UBS has written to shareholders in an effort to rally support for its plan to shore up its balance sheet by raising capital from Asian and Middle Eastern investors, ahead of an extraordinary meeting to vote on the deal next month.

The Swiss bank’s chairman, Marcel Ospel, and chief executive Marcel Rohner yesterday wrote to shareholders outlining the rationale for the decision to raise fresh capital by selling convertible loan notes to the Government of Singapore Investment Corp and another investor. The deal will ultimately give the two investors a stake in the bank.