Dive Brief: 

• Facebook announced this week that it will begin running ads on third-party mobile apps, building the foundation for a mobile ad network. 
• In the announcement, Facebook was short on details, but said the test was limited to a few advertisers and partners. 
• The social network isn't accepting any new advertisers currently for the mobile ad network, but has provided an opt-in form for those interested in being involved in the future. 

Dive Insight: 

Building a mobile ad network that reaches far past its own platform could be a huge money maker for Facebook. While a Facebook-run mobile ad network will have many advantages, it does draw into question whether or not the social giant would overshadow other networks to the point of a monopoly. It will be interesting to see what information Facebook decides to share after the first round of testing.