YouTube is to increase its ad prices in 2018, according to Business Insider. Prices could rise by as much as 20% for advertising space on some of YouTube's top channels. The prices hikes will apply to “reserved inventory” that is bought ahead of time on a fixed CPM or CPD basis, rather than via an auction. Ad types included in this “reserved inventory” category include masthead ads and certain types of in-stream ads. The raising of prices comes after a difficult year for YouTube, which has been rocked by several scandals involving ads appearing alongside extremist content. It seems that the price hike is meant to reflect the fact that these “reserved inventory” ads are a premium option that guarantee brand safety.