UBS shook off some scepticism about its turnaround plans by reporting a surge in new clients for its private bank in the first quarter as well as a solid performance by its investment bank.

UBS, one of the hardest-hit banks during the financial crisis, is striving to reach a series of aggressive profit and revenue goals and show that chief executive Oswald Gruebel's turnaround plan is working. However, investors have been sceptical of the plan, particularly given the far tougher regulations put in place since Gruebel announced his targets in November 2009.