Microsoft is in discussions with five giant advertising companies a deal to buy its digital ad agency Razorfish -- and to use Microsoft's advertising technologies and possibly buy "hundreds of millions of dollars" of ad space across its Web properties -- according to executives familiar with the situation. Companies pitched including: WPP, Omnicom Group and Publicis Groupe. Microsoft has also been in contact with Interpublic Group and Dentsu, according to people familiar, reports Wall Street Journal. Microsoft acquired Razorfish as part of its $6 billion acquisition of aQuantive.