Swiss banking giant UBS said Thursday it was to dramatically cut back its investment bank arm, reducing its risky assets by half or 145 billion Swiss francs (117 billion euros). \"We have chosen to substantially reduce the risk profile of the bank by exiting and downsizing businesses which are not value added (for) our client franchise or deliver unattractive risk-adjusted returns,\" newly-appointed chief executive Sergio Ermotti said in a statement. The shake-up comes as the bank, Switzerland\'s largest, tries to draw a line under a disastrous period which has seen it battered by the global financial crisis and embroiled in disputes over client secrecy. The decision follows a review by the board of directors and group executive board. Ermotti, 51, was appointed head of UBS on Tuesday after the departure in September of Oswald Gruebel in the wake of a massive rogue trading scandal, another blot on the bank\'s record. The board also announced that former Bundesbank president Axel Weber will succeed Kaspar Villiger as board chairman from May 2012, a year earlier than planned. The investment bank will be \"more focused and less complex,\" UBS said on Thursday, while revealing that the number of people it employs is expected to be around 16,000 by the end of 2016 compared with 18,000 currently. Among other key announcements were a proposed dividend of 0.10 Swiss francs per share for 2011 \"and a progressive capital return programme thereafter.\" The bank is targetting a common equity Tier 1 capital ratio target of 13 percent -- a measure of its financial strength -- under the new Basel III international financial regulations. The core Tier target under Basel III is 7.0 percent but larger banks, whose failure whould pose a risk to the whole financial system, are expected to increase that to at least 9.0 percent. \"UBS is acting from a position of strength and we are adapting our strategy to deliver more attractive returns to shareholders and to reflect economic and regulatory change,\" Ermotti said. \"We are confident that we can deliver a return on equity between 12 percent and 17 percent and we are determined to return capital to our shareholders.\" While addressing an investors\' day in New York on the strategy changes, Ermotti also sought to reassure customers and clients over the recent $2.3 billion (1.67 billion euro) rogue trading scandal. \"We are committed to addressing the causes of the incident and disciplining those who are ultimitely deemed responsible,\" he said. London equities trader Kweku Adoboli currently faces two charges of fraud and two of false accounting in connection with the losses. The investment bank was previously hit by colossal losses during the US subprime loan crisis and has struggled to rebuild itself, posting the worst performance of the banking group in the third quarter with pre-tax losses of 650 million Swiss francs, worse than the year-earlier loss of 406 million Swiss francs. UBS posted a third-quarter net profit of 1.018 billion francs (831 million euros, $1.16 billion) however. In 2008 and 2009, UBS got embroiled in a serious tax evasion spat with the United States as the Swiss tradition of banking secrecy was undercut. It was forced to hand over 300 client names and pay a 780-million-dollar fine in a first case, before a second wider case in which it finally agreed to hand over data on 4,450 American clients.