26-year-old innovator cashes in on $1.1 billion Tumblr sale

forbes copy (2)

David Karp, the brains behind social media sensation Tumblr, made Forbes’ 30 Under 30 list this year as one of the world’s richest young entrepreneurs.

David Karp, the brains behind social media sensation Tumblr, made Forbes’ 30 Under 30 list this year as one of the world’s richest young entrepreneurs.