"Enterprise portals as software have been around for a good ten years now and there has always been a tension between wanting to provide enterprise integration and servicing the lightweight collaboration space," said CMS Watch founder Tony Byrne.
"In the past two years Microsoft has become the dominant player for lightweight collaboration so the marketplace is reacting."
In particular, the large portal vendors are looking to exploit the fact that SharePoint lacks a comprehensive way to integrate with non-.Net enterprise technologies like many ERP and CRM systems, added Byrne.
The report also found that SharePoint is under attack from a plethora of open source alternatives – such as Apache, eXo and Liferay – which are undergoing rapid expansion at the moment.