CHART OF THE DAY: A Look At Facebook's Exploding Mobile Ad Business

When Facebook filed to go public, it warned that it made no money from its mobile user base.

"We do not currently directly generate any meaningful revenue from the use of Facebook mobile products, and our ability to do so successfully is unproven," said Facebook in its filing to go public.

A year later, it's a completely different story for Facebook.

The company generated $656 million from mobile advertising, 41% of its total ad revenue, and 36% of its total revenue, in the second quarter of 2013.

As you can see in this chart, Facebook's mobile business is exploding, which is good since the rest of the business is relatively stagnant.