While Google remains the overwhelming market leader, Bing is making substantial gains in the search engine market.

According to a new report from the digital marketing firm Efficient Frontier, Bing has increased its search engine market share in both the spend and click categories, to 6.5 percent and 5.5 percent respectively.

Bing’s gains come largely at Yahoo’s losses. Yahoo’s spend share dropped from 22.7 percent in Q4 2009 to 18.7 percent in Q1 2010, and is down from 21.3 percent in Q1 2009. Yahoo’s click share decreased from 22.7 percent in Q4 2009 to 20.5 percent in Q1 2010, and is down from 24.2 percent in Q1 2009.

In the click and spend categories, Bing has shown the highest year-over-year growth, up 45 percent, while Yahoo was down and Google remained consistent. Bing’s biggest sector is in the travel sector, where it takes up 9.3 percent of the searches.

Last year, Microsoft and Yahoo signed an agreement, in which Yahoo became the sales force for both Bing and Yahoo search engines, while Microsoft’s Bing search engine would power Yahoo. Since the deal was signed, Yahoo’s search engine has lost significant ground to Bing. Though Bing is still too insignificant to radically change search engine optimization (SEO) techniques radically, its continuing expansion could lead to changes in the future.

Katherine Griwert is Brafton's Marketing Director. She's practiced content marketing, SEO and social marketing for over five years, and her enthusiasm for new media has even deeper roots. Katherine holds a degree in American Studies from Boston College, and her writing is featured in a number of web publications.