Invirtus acquisition by Quest remained stealth until June 2007, when finally emerged online. Despite that nor Quest neither Invirtus ever confirmed.
No official press releases has been released so far but now Invirtus company profile on official website clearly exposes the news (and real acquisition period):
In early 2007 Quest Software, Inc. acquired Invirtus in order to expand its product portfolio of virtualization infrastructure management solutions. The virtualization management technologies from Invirtus support that objective, by helping enterprises maximize their virtualization investment, whether based on Microsoft, VMware or Virtual Iron platforms…
After acquisition Quest started to work on Invirtus strategy, first allowing Scott Herold to move from its other virtualization company Vizioncore, and then arranging an OEM partnership between two subsidiaries.