"In order to be the deal of the century we need to work hard in the next two or three years," Sergio Ermotti said while taking part in a panel discussion at the World Economic Forum in Davos.

"It is not a present, it is nothing for free so [there is] still hard work to be done."

At the same panel discussion JP Morgan's Mary Callahan Erdoes, CEO of the U.S. bank's asset and wealth management division, said rates were probably going to stay higher for longer and markets should prepare for massive volatility.

(Reporting by Noele Illien in Zurich, Editing by Louise Heavens)