Why Tumblr is Worth $1.1 Billion To Yahoo May 23, 2013 - Last Modified: May 23, 2013 by Hesham Zebida Yahoo CEO Marissa Mayer and Tumblr CEO David Karp reached a deal for Yahoo to buy the blog platform for $1.1 billion in cash. Read the full story: Tumblr is Worth $1.1 Billion →