• by Laurie Sullivan , Staff Writer @lauriesullivan, September 16, 2010

August search market share numbers from comScore out late Wednesday reveal Yahoo gaining U.S. search market share for the second consecutive month, increasing to 21%, up from 20%, sequentially.

Google failed to gain market share in August. The Mountain View, Calif., company's share fell to 60.4% in August, from 61.6% in July. Share loss has become a bigger concern for Google, Piper Jaffray Analyst Gene Munster wrote in a research note published Thursday. "The bottom line is it appears at least Yahoo's search market share has bottomed, while Google is losing some share due to the lack of content-based offerings like slideshows," Munster explains.

Americans conducted more than 16.9 billion total core search queries in August 2010. That means on an explicit basis, which excludes searches not generated through a traditional text box, overall search volume increased 13% in August, compared with the prior year.

Yahoo gained explicit share slightly to 17.4% in August from 17.1% in July. Google lost sequential share, slightly, slipping to 65.4% in August from 65.8% in July. Microsoft sites grew slightly, taking 11.1% in August, up from 11.0% in July. Both Ask Network's and AOL's core search market share remained flat at 3.8%, and 2.3%, respectively.

What are the top search terms in the past seven days? Google Insights for Search suggests in the United States people have been searching for "facebook," "yahoo," "you," "youtube," "google," "craigslist," "games," "news," "hotmail," and "weather." The top rising searches include "ines sainz," "vma 2010," and "lady gaga."

Although Google's sequential share loss seems troubling, Munster believes Google Instant could help reverse query share loss in the coming months.

People searching on keywords may have an easier time finding what they need with Google Instant, but some SEO experts suggest keeping a close eye on Google AdWords as it relates to Google Instant. Providing some examples, David Iwanow, marketing director at The Lost Agency, a web analytics focused search agency, believes those who optimize sites will need to spend more time examining existing projects and revising current link-building strategies.

Aside from detailing issues around click-through rates, Iwanow also delves into some themes around censorship related to search terms that violate Google's auto-complete policies. He explains this occurs when Google shows a blank screen that requires searchers to hit "enter" to see results. He says no big change from what searchers did before, but it may change user behavior for some when they think that they get zero results. This also could reduce the amount of searches on Google.