For its first acquisition in its 11-year history, the news Web site MSNBC has bought the social media news network Newsvine for an undisclosed sum.

MSNBC, an independently run joint venture between Microsoft and U.S. broadcaster NBC, and Newsvine, a two-year-old Web start-up, are both based in Seattle.

MSNBC has 29 million unique users, while Newsvine averages 1 million uniques. The coupling is aimed at spreading participatory news, reported Brand Republic.

Newsvine, which allows users to post published news stories that can then be discussed and ranked by other users as well as allowing them to write their own stories, will continue to operate independently, while MSNBC may adopt Newsvine's features and user-generated content.

Newsvine was founded in 2005 with $1.5 million, backed by venture capital, by former Disney and ESPN executives.

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