Marketers in the US are continuing to invest heavily in mobile paid search across Google and Bing/Yahoo, with the total spend on tablets and smartphones up 65.9% year-on-year to 28.7% of search budgets.

Taken individually, spend on tablets increased 87.6% compared to Q3 2012, while the increase on smartphone was 118.1% in the same period.

The increased investment is unsurprising considering the consumer shift towards mobile search and the recent roll out of Google’s Enhanced Campaigns. 

Data included in our own Mobile Commerce Compendium shows that search is one of the top three most popular smartphone activities behind email and making calls, so it’s inevitable that marketers will begin ramping up their investment in this channel. 

The Search Agency’s State of Search Report also shows that the share of impressions from tablets increased by 34.7% year-on-year and 7.3% compared to Q2. Overall tablet devices now account for 11.8% of total paid search impressions on Google.

In comparison, smartphone impressions fell to 13%, a 6.6% decrease quarter-on-quarter, while desktop impressions remained relatively unchanged.

Looking at the stats from Bing/Yahoo, 5.5% of impressions came from tablets, 7.5% came from smartphones and 86.9% came from desktops.

The report also looks at how the share of clicks is spread out by device. It shows that both smartphones and tablets gained click share at the expense of desktop on Google. 

In fact, for the first time smartphones and tablets made up more than one-third of total clicks on Google in Q3.

Over on Bing/Yahoo, smartphone click share increased 7.5% compared to Q2, while desktop and tablet click share remained relatively unchanged. Smartphones and tablets made up a combined 17.7% of total clicks on Bing in Q3.

Overall Google achieved a significantly greater impression growth in Q3 compared to Bing, which may have come as a result of Enhanced Campaigns. This update to Google’s paid search platform removed the ability for advertisers to run separate mobile and desktop campaigns, so brands are forced to bid on all three devices. 

While average CPC on Google and Bing were nearly identical in Q3 2012, Bing CPC has been increasing at a much faster rate and was 12.7% higher than Google in Q3 2013.

The research is based on analysis of US client data from advertisers who had fifteen consecutive months of data with The Search Agency and an established and stable business model from Q3 2012 to Q3 2013.