Daimler's largest investor, the oil rich emirate of Abu Dhabi, is preparing to sell its 9 percent stake in the German automotive group, two sources familiar with the situation told Reuters on Thursday, confirming a magazine report.

Abu Dhabi has been mulling an exit for some time now, said one of the sources.

The emirate's sovereign wealth fund Aabar became Daimler's largest investor after buying a 9.1 percent holding for 1.95 billion euros ($2.6 billion) in 2009.

The German carmaker's share price has since doubled, meaning the stake now has a market value of just over 4 billion euros.

A Daimler spokesman said the car maker had no knowledge of any plans by Aabar to reduce its Daimler stake, adding that there had been no talks with Aarbar on the matter.

(Reporting by Philipp Halstrick and Hendrick Sackmann)