UPDATE 1-Deutsche Bank CEO urges study of financial bubbles

* Ackermann says worst phase of financial crisis over

* Says financial bubbles need to be studied

* Deutsche Bank shares up 0.9 percent

(Adds details, CEO comments)

FRANKFURT, Nov 20 (Reuters) - Deutsche Bank AG (DBKGn.DE) Chief Executive Josef Ackermann said the worst parts of the financial crisis were past but said more time needed to be spent studying how financial bubbles occur.

"A very valid question is how to prevent another crisis," Ackermann told a Frankfurt banking conference.

In particular, the emergence of financial bubbles needs to be studied, Ackermann said, noting regulators, bankers and politicians did not seem to have made much progress identifying financial bubbles since the Dutch tulip craze of the seventeenth century.

A recent recovery of asset prices and markets is not a reason to become complacent since this was a sign of a fragile recovery, at best, said Ackermann, who is also chairman of bank lobby group the International Institute of Finance.

Shares of Deutsche Bank were up 0.9 percent at 57.83 euros by 0904 GMT, while Germany's blue-chip index .GDAXI was up 0.6 percent. (Editing by David Holmes) ($1=.6722 Euro)