The research firm put together a top 10 list, which you can find here.
In second place, but well behind Tumblr, is Right Media, which Yahoo purchase in 2007 for $850 million, CB Insights notes. Redpoint Ventures and WGI Group were backers.
At No. 3 is is Buddy Media, which sold last year for $745 million to Salesforce. Its backers included GGV Capital, Greycroft Partners and Institutional Venture Partners.
The rest of the list follows in a table courtesy of CB Insights.
Note that the list does not include DoubleClick, which Google purchased for $3.1 billion after DoubleClick went public.
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