Spend on social advertising grew by 50% year-on-year during the final quarter of 2015. The channel’s growth rate was six times that of search marketing, which noted an expenditure increase of just eight per cent, according to new research. Mobile was found to be the biggest driver of overall growth across both channels, accounting for almost all of the annual ad spend increase in paid search. The findings were outlined in Kenshoo’s most recent Digital Marketing Snapshot study.