VMware shares suffered their biggest fall in six months after the surprise announcement that founder and chief executive Diane Greene has left the company.

The virtualisation specialist also warned that full-year sales for 2008 are likely to be “modestly below” previous expectations of 50 per cent year-on-year growth.

Greene has been replaced by former Microsoft executive Paul Maritz, who was previously president of a division of VMware’s parent company, EMC.

Wall Street analysts are speculating that Greene may have fallen out with EMC executives over the future of VMware.

EMC bought the company for $635m (£323m) in 2004, subsequently selling a stake on the New York Stock Exchange last year for $1.1bn (£560m). EMC now owns about 86 per cent of VMware, but Greene may have been pushing for further independence.

“As one of the founders and the leader of VMware, Diane guided the creation and development of a company that is changing the way that people think about computing,” said Joe Tucci, EMC chief executive and chairman of VMware’s board of directors

“The board thanks her for her considerable contributions to VMware and wishes her every success in the future.”