Research by WARC has predicted that global mobile ad spend will hit 98.3 billion US dollars this year, equivalent to 23% of all ad spend. The amount of money spent on mobile advertising is up 35% on last year, meaning that mobile is now the world's second largest ad medium. 51% of this mobile ad spend is going on search advertising, followed by display advertising at 45%, with classified ads and other ad spend making up the remaining 4%. Looking at the advertising landscape more generally, the study found that the duopoly of Google and Facebook is becoming stronger. Advertising expenditure on these two platforms is set to account for 61% of all online ad spend this year, up from 58% last year.