Earlier this month, UBS posted third quarter net losses of $556 million, which was partly attributed to a decision by the Swiss government to exit from its investment with the firm.
But Mr Gruebel told investors that he was determined to make the financial institution profitable in every sector it operates in, as well as becoming the leading client-focused investment bank.
His medium-term aims for the bank, a period UBS defined as three to five years, include a cost-to-income ratio of between 65 to 70 per cent, along with a return on equity of up to 20 per cent.
"The transformation we are undertaking is a fundamental one and it will not happen quickly," Mr Gruebel admitted.
"I am determined, however, that we build a firm for sustainable profit and not one to focus only on short-term expectations".
By Tony Aynsley