New York—While marketers have flocked to Facebook as a key social channel, they remain underinvolved in advertising on the site, according to a study by Advertising Age and Citigroup. According to the “Ad Age/Citigroup Facebook Survey,” 86% of respondents said they use Facebook as a marketing tactic but only 55% said they advertise on the channel; 88% said they would implement Facebook content without advertising at all. Some of that may be due to budget allocations: 47% said their digital ad budgets were less than 20% of their total marketing budgets, with 50% pegging social budgets specifically at less than 10%. The study was based on an online poll this month of 658 self-described social marketing decision-makers. Ad Age is a sibling publication of BtoB.