• by David Goetzl  @dgoetzl, June 21, 2013

Ad spending soared at Twitter and YouTube in May, while they dropped slightly at Yahoo and Facebook. Twitter dollars jumped 95%, while YouTube was up 43% compared to May 2012. Yahoo fell 4% and Facebook was down 1%.

The figures come from combined spending by four large holding companies -- Aegis, Havas, Interpublic and Publicis -- representing about 60% of total agency spend.

Total digital dollars for the top-20 digital vendors in May were up 42% versus last year, according to Standard Media Index (SMI), which monitors actual booking data at the four large groups. Digital had its largest one-month year-over-year gain since August 2010.

The drops at Yahoo and Facebook in May were well below the double-digit declines each has experienced in total over the first five months of the year. SMI figures show Yahoo is down 15% and Facebook has dropped 17%.

Google, which is listed separately from its YouTube unit, dominates the top 20 in share at 13.7% in May, when it had a 4% growth.

Within the broad digital category, SMI data shows that mobile spending leaped 122% in May, while spending on online video was up 92%. Spending on exchange-based digital platforms increased 87% for the four holding companies combined, while social media increased 54%.

Behind digital, out-of-home was the category with the second-highest growth last month, up 31%. Radio (18%) and magazines (16%) both more than doubled total TV (7%). Newspapers fell 8%.

For the first five months of the year combined, total TV (61.4%) gained share in the overall ad market versus the broad digital category (23.5%).

SMI zeroed in on ABC’s multiple properties to provide a sense of how a brand is performing across platforms. May spending on the broadcast network was up 18%, while the owned stations saw a 4% bump. In the digital arena, the brand saw massive gains, up 105% in display ads and 70% in online video.