Searchers used Bing less in September than in previous months, ending three consecutive months of growth.
Microsoft (NSDQ: MSFT)'s Bing search engine lost market share for the first time since its launch in May and its Internet Explorer browser continued its long, slow slide.
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But in the calm before the ad blitz, Microsoft's search and browser power is suffering.
Bing lost 0.2 percentage points, dropping to a 3.39% share of the global search market, according to NetApplictions. Google lost a similar number of percentage points, dropping to 83.13% global search share. Yahoo (NSDQ: YHOO) lost 0.44 percentage points to end up at 6.84%.
A different metrics firm, StatCounter, said that Bing declined slightly on a global basis, from 3.58% to 3.25%, a drop mirrored by Yahoo, which fell from 4.84% to 4.37%.
Globally, StatCount saw Google (NSDQ: GOOG) gaining rather than slipping, as NetApplications did: Google's global search share increased to 90.54% in September, from 89.57% in August, according to StatCounter's yardstick.
StatCounter's figures also show Google US search share rising to 80.08% in September from 77.83% in August.
Bing's share of the US search market in September dropped to 8.51% from 9.64% in August, according to StatCounter. Yahoo's US search share during this period dropped from 10.5% to 9.4%.
With regard to Web browser usage, Internet Explorer went from 58.69% in August to 58.37% in September, as StatCounter reports. According to NetApplications, Internet Explorer's decline went from 66.97% to 65.71%.
Firefox reached a global market share of 23.75%, according to NetApplications, a level just below its 23.84% high-water mark in April. Google's Chrome browser and Apple's Safari browser also posted gains to end up at 3.17% and 4.24% respectively.
As StatCounter sees it, Chrome actually passed Safari in August and increased its lead in September. Chrome finished the month with global market share of 3.69% while Safari came in at 3.28%.