Facebook accounted for 1 in 3 display ads online in the first quarter, according to comScore. Overall, 1.11 trillion display ads were delivered in the first quarter.
Of that sum, Facebook delivered 346 billion impressions.
Here's a look at the standings. In a nutshell, Facebook and Yahoo lead the field by a wide margin.
As far as the top advertisers go it's all about telecom, credit reports and finance.