To be exact, EMC bought vmware in late 2003 and the acquisition closed in 2004. http://www.vmware.com/company/news/releases/emc2.html Then EMC spun VMware off on its own with the IPO in 2007, still remaining a shareholder, but VMware is its own public entity of which EMC is a part owner. http://www.vmware.com/company/news/releases/IPOpricing.html