A growing number of global brands have pulled their advertising campaigns from YouTube over the past week after finding their ads had appeared next to extremist content. Google, which owns YouTube, has vowed to tackle the issue by working on toughening up its policies, making its advertiser controls easier to use, and hiring more staff to police content deemed unsafe by advertisers. However, as this illustrative chart from Enders Analysis shows, at least some of the blame for such ad misplacement falls on the ad buyers themselves: Enders Analysis The chart demonstrates that the cheapest ads — bought using automated systems on ad exchanges that serve ads to a swathe of sites across the web — carry the most risk, whereas ads that have been directly sold by a media owner — and particularly broadcasters — are deemed the most safe. "YouTube Preferred" — a service where advertisers pay a premium to only appear against the most popular videos — also appears quite high up the chart.