Microsoft has written off $6.2bn of the value of aQuantive, bought in 2007

"Microsoft has written off nearly the entire value of aQuantive, the ad tech company it bought for $6.3 billion in 2007.
The aQuantive deal was Microsoft's biggest acquisition until the company bought Skype for $8.5 billion last year. It came, too, at a heady time for tech acquisitions. Google had just bought DoubleClick for $3.1 billion, part of a years-long effort to build out the pipes of online advertising.
Microsoft reacted by buying aQuantive, and briefly held a formidable position in ad tech, with a leading ad network (Drive PM), an ad server (Atlas) and its own digital agency (Razorfish).
But while Google focused on display, and particularly the technology that enables it, Microsoft turned its attention to search. Today the company revealed what it really thinks the unit is worth by writing down $6.2 billion related to the deal.
"While the aQuantive acquisition continues to provide tools for Microsoft's online advertising efforts, the acquisition did not accelerate growth to the degree anticipated, contributing to the write down," Microsoft said in a statement.
[...]
It sold Razorfish to Publicis for $530 million in 2009."
Source:  AdAge, 2nd July 2012