Dive Brief: 

• Tumblr has announced that it will allow brands and advertisers to purchase "Sponsored Trending Blog" placements on its mobile app. 
• This is Tumblr's second ad product on mobile and fifth overall. 
• The first brands to try out the new ad offerings include Turner Broadcasting, Delta, Calvin Klein and Sony Pictures Entertainment. 

Dive Insight: 

Tumblr is following in the footsteps of other social networks, like Twitter, which sell spots in their trending sections. Tumblr is still uncharted territory when it comes to the effectiveness of ads because the platform is so new to offering them. Tumblr's engaged audience is attractive to many brands, and the fact that this product focuses on mobile is just another perk.