Sergio Ermotto was called on in September to replace Oswald Grubel, who quit suddenly in the wake of a massive fraud perpetrated by 31-year-old UBS trader Kweku Adoboli.
According to an unnamed source from within the bank quoted by the paper, if the board does not choose its new chief executive by December 15th, this would mean the UBS was looking outside the company to fill the post.
On Tuesday UBS posted third-quarter net profit of 1.018 billion francs ($1.16 billion) even though it had to take a massive charge due to the rogue trading scandal.
The German central bank meanwhile cleared the way for its former chief Axel Weber to act as an advisor for UBS and help it find a new chief executive.
Weber will then join UBS's supervisory board in May and the bank hopes to appoint him as supervisory board chief in 2013.