Bing and Yahoo together commanded 21% of U.S. paid search spending in the first quarter of 2013, up from 18.6% in the fourth quarter of 2012 and 18% in the first quarter of 2012, says online marketing firm The Search Agency.  Microsoft Corp. has provided search results from its Bing search engine for Yahoo Inc.’s web sites since 2010.

Google Inc., though, continues to dominate, accounting for 79% of U.S. paid search spending in Q1, down from 81.4% in the fourth quarter of 2012 and 82% in the first quarter of 2012.

Overall, U.S. paid search spending increased 21.6% year over year in Q1 and 8.2% quarter over quarter. The report gave no actual spending figures.

The Search Agency released its Q1 “State of Paid Search” report today. The report uses data aggregated from the marketing firm’s clients in various industries, including retail. The agency declines to specify the number of clients included.

Most of Bing and Yahoo’s Q1 paid search growth came from increased spending on tablets, the report says. In the first quarter, 15.3% of total paid search spending on tablets went to Yahoo-Bing, up from 11.2% in Q4 2012 and 10.6% in the first quarter of 2012.

“Bing has been ferociously working to grab market share from Google, particularly battling it out on tablet devices,” says Keith Wilson, vice president of agency products at The Search Agency. “The study also showed tablets continue to be a driving force—consumers are hitting the tablets to shop and buy, with tablet performance steadily increasing over the past five quarters. I don’t see this slowing anytime soon.”

Of all industries, e-retail garnered the most clicks from paid search ads, 39.6%, on tablets in Q1, the report says.

For the fifth consecutive quarter, retailers have won steady increases on clicks from mobile devices. In Q1, retailers’ share of total search ad clicks from smartphones increased 78.2% year over year, and 69.9% from Q4 2012 to Q1 2013. Retailers’ share of total clicks from tablets was up 71.8% year over year and 13.5% from Q4 to Q1, the report says. On all devices, clicks across both Google and Bing/Yahoo were up 11.7% year over year and 8.7% from Q4 to Q1.

Retailers’ spending on paid search ads in the first quarter of 2013 declined 9% from the fourth quarter of 2012. The Search Agency says. Accordingly, retail clicks decreased 9.2% from the fourth quarter, though they were up 10.1% year over year, it says. The quarterly dip in paid search spending and clicks was expected following the holidays in Q4, the report explains, and will likely rebound in the coming months.

Though dampened, e-retailers’ paid search spending in Q1 was somewhat more cost-effective than in previous quarters, according to the report. Their click-through rates—how often consumers click on ads versus how often a search engine displays them—in the first quarter were up 54.5% over Q4 and up 30.1% year over year, The Search Agency says. And while the average cost-per-click increased 22% year over year in Q1, it decreased 1.8% from the previous quarter. Retailers spent slightly less than other advertisers on the average click on a paid search ad in Q1, $0.73 per click versus $0.76 for all industries, the report says.

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