UBS on Thursday provided long-awaited details on its plan to shrink its investment bank by unwinding risky assets and to put more focus on its profitable business of managing the wealth of rich clients.

"We have chosen to substantially reduce the risk profile of the bank by exiting and downsizing businesses which aren't value added to our client franchise or deliver unattractive risk-adjusted returns," the bank's new chief executive, Sergio Ermotti, told investors at a presentation in New York.