Microsoft and Yahoo just finished transitioning the smaller company's websites to run the Bing search engine backend platform earlier this week, making it too early to assess whether the combination will pick up any market share vis-à-vis Google in a gambit that could tilt search marketers' spending priorities.

But according to market tracker Nielsen Company, the latest numbers for July show that Microsoft's (NASDAQ: MSFT) Bing search engine handled 13.6 percent of all U.S. searches while Yahoo (NASDAQ: YHOO) served 14.3 percent. Meanwhile, Google (NASDAQ: GOOG) served up 64.2 percent of U.S. searches.

Those figures translated into a 1 percent decline in market share for Google from June, while Yahoo gained 4 percent, and Bing picked up 2 percent.

Year-over-year comparisons, however, put the figures in a somewhat different light. Since July 2009, for instance, Yahoo has lost 17 percent of its overall market share. In that same time, Bing improved its share by 51 percent from a year earlier. That gain, though, appears to come at the expense of Microsoft's new partner, Yahoo, because in the same year-over-year comparison, Google only lost 1 percent of its share, according to Nielsen.

Microsoft and Yahoo announced earlier this week that Bing's search technology is now in place and is providing search results to Yahoo's sites, demonstrated by the "Powered by Bing" logo appearing at the bottom of Yahoo search results pages. Had that transition already been accomplished for the month of July, the search figures would have given the two companies a combined share of U.S. searches of 27.9 percent.

But since the integration was only completed in the latter part of this month, their combined results will not show up until Web analytics firms report rankings for September.

Meanwhile, for June, Nielsen reported that Google held a 65 percent share of U.S. searches compared to 13.7 percent for Yahoo, and 13.4 percent for Bing. If the Bing integration had occurred at that time, their combined results would have been 27.1 percent total share for June.

Microsoft and Yahoo agreed to the 10-year search deal last year and got final regulatory approval to use the Bing technology on Yahoo sites in return for sharing advertising revenues in February.

Stuart J. Johnston is a contributing writer at InternetNews.com, the news service of Internet.com, the network for technology professionals. Follow him on Twitter @stuartj1000.

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