Here’s the updated list in terms of monthly unique visitors:
1. Millennial: 45.6 million
2. Yahoo: 36.1 million
3. Google: 31.9 million
4. AOL/Platform-A’s Third Screen Media: 28.6 million
5. AdMob: 25.7 million
6. Microsoft’s MSN Ad Network: 25.4 million
7. Jumptap: 23.4 million
8. Quattro Wireless: 23 million
via The Real List Of The Largest Mobile Ad Networks—Sort Of | mocoNews.