* UBS CFO John Cryan to step down from end of May, 2001
* UBS says Cryan stepping down for personal reasons
* UBS veteran Tom Naratil to replace Cryan
* UBS brings in UniCredit's Sergio Ermotti to head EMEA
(Adds analyst, background)
ZURICH, Dec 3 (Reuters) - UBS veteran Tom Naratil will next May succeed Chief Financial Officer John Cryan, who saw the Swiss bank through one of its toughest times, in chief executive Oswald Gruebel's latest surprise management shake-up.
Sergio Ermotti from Italy's UniCredit will take up the role of chairman and chief of Europe, Middle East and Africa (EMEA), UBS also said in a statement on Friday.
The decision of Cryan, who will turn 50 on Dec. 16, to leave the bank comes as investors speculate about when Chief Executive Oswald Gruebel and Chairman Kaspar Villiger, who were brought from retirement to clean up the bank, would leave.
Analysts said Cryan's departure was as a surprise. "Cryan was very well liked, and people will be pretty disappointed," said one London-based analyst, who did not want to be named, adding that UBS shares might come under a little pressure.
"We don't really know the new person (Naratil), so it's hard to judge," the analyst said.
Cryan took over the position as CFO at the height of the financial crisis in 2008, right before the government had to bail out the bank, and he helped in its rebuilding.
UBS, Switzerland's biggest bank, stopped bleeding client money in the third quarter for the first time since early 2008, though a shock investment banking loss on sluggish trading soured the news that the bank had met this key turnaround goal.
The 49-year old Naratil has worked at the bank since 2000 and has held a number of senior roles within the company, including Chief Financial Officer & Chief Risk Officer, Wealth Management Americas, UBS said.
Ermotti was head of investment banking at UniCredit, but in October the bank said he was leaving after he was passed over for the chief executive post.
Ermotti, 50, joined UniCredit at the end of 2005 as head of the markets and investment banking division, after working at Merrill Lynch for nearly 18 years.
At Merrill, Ermotti worked in Switzerland, London and New York. Born in Switzerland's Italian-speaking canton of Ticino, he is an Oxford management graduate and has a Swiss banking master's degree. (Reporting by Katie Reid and Sven Egenter in Zurich and Steve Slater and Sarah White in London; Editing by Will Waterman)