Nielsen//NetRatings earlier this year named as one of the 10 websites that have had the greatest impact on the web and on society.
The deal will see acquire 100% of Kelkoo, one of the largest European e-commerce sites with operations in nine countries including the UK.
Kelkoo allows web users to quickly find and compare product prices from more than 2,500 online retailers across a wide range of sectors including books, music, games, travel and consumer electronics.
Yahoo! says the deal will strengthen its European business, significantly adding to its global e-commerce business and search-related online marketing services provided through its Overture subsidiary.
Terry Semel, chairman and chief executive officer of Yahoo!, said: "Commerce has emerged as a key component of search and the combination of web search, product search and comparison shopping will help further Yahoo!'s goal to create the most comprehensive and best user experience on the web globally."
He added that Kelkoo would add depth and breadth to Yahoo!'s integrated network of services for consumers, as well as creating another way for marketers seeking to reach them.
Kelkoo was founded in France in November 1999 and has since merged with or acquired several companies in the UK, Spain, Norway and France. The company has been profitable since the fourth quarter of 2002 and currently employs around 250 people.
Pierre Chappaz, chief executive officer and founder of Kelkoo, said: "We believe the combination of Kelkoo's comparison shopping service with Yahoo!'s global reach and commitment to being the leader in search and commerce will help Kelkoo extend its leading presence in Europe."
Kelkoo will become a subsidiary of Yahoo! following completion of the deal and Chappaz will continue to lead Kelkoo's operations reporting to John Marcom, senior vice-president of international operations at Yahoo!.
If you have an opinion on this or any other issue raised on Brand Republic, join the debate in the .