Microsoft's share of the U.S. search market grew last month to its highest point since the launch of its Bing search engine. But that market share growth continues to come at the expense of Yahoo, rather than market leader Google.
That's likely to be of some concern considering that Microsoft (NASDAQ: MSFT) is counting on its pending search outsourcing deal with Yahoo (NASDAQ: YHOO) -- a marriage of the No. 3 and No. 2 players in search -- to help it better compete with Google (NASDAQ: GOOG).
According to Web analytics firm comScore (NASDAQ: SCOR), seven-month-old Bing served 10.7 percent of U.S. searches last month. That's up from 10.3 percent market share in comScore's November rankings, and the seventh-straight month that Bing has gained share since it debuted in June, comScore said in a note to customers on Thursday.
Yahoo, meanwhile, appears to continue its slow spiral down, though it remains in second place. In December, Microsoft's new partner slipped to its lowest level in comScore's rankings, coming in at 17.3 percent. Although that's a mere 0.2 percent off from November's 17.5 percent, in October, Yahoo lost a half point from 18 percent.
In the meantime, besides Bing, the other clear winner was once again Google, which grew slightly from 65.6 percent of U.S. searches in November, to 65.7 percent.
That figure constitutes Google's highest share thus far, according to comScore.
The latest numbers are very similar to December's search rankings by analytics firm Nielsen, released on Wednesday.
Nielsen's and comScore's numbers suggest similar trends. However, the firms use different criteria in their measurement and weighting schemes, so they are not directly comparable.
For instance, in Nielsen's rankings, Bing was down from 10.7 percent in November to 9.9 percent of U.S. searches in December. Also, according to Nielsen's numbers, Yahoo slid from 15.3 percent in November to 14.4 percent, and Google grew to 67.3 percent from 65.4 in November.
In any event, the news suggests that even a combined Bing and Yahoo effort would have a sizable challenge ahead of it before it can seriously challenge Google's lead.
In December, Microsoft and Yahoo finally signed their ten-year deal for Bing to supply the search infrastructure for Yahoo's sites in exchange for some of the ad revenues those sites yield.
That deal is awaiting regulatory approval, which Microsoft executives have said they hope to receive early this year.
Microsoft CEO Steve Ballmer said in June that he is so serious about becoming a dominant player in search that he is willing to invest billions -- between 5 and 10 percent of Microsoft's operating income over five years -- in the endeavor.