This chart shows that Facebook appeals greatly to small advertisers, likely due to its intuitive advertising interface minimizing barriers to entry. It is important to note, however, that Facebook is still competitive with Yahoo! and Microsoft when vying for ad dollars from large brand advertisers. In Q3 2011, Facebook served more ad impressions for the Top 100 advertisers than Microsoft did and only slightly less than Yahoo! did.
Facebook Attracts Smaller Advertisers