The results show Google's Web search resiliency at a time when the company is increasingly launching sorties in other areas, including mobile phones and digital books. The figures show that Microsoft has its work cut out for it as it attempts to mount a credible search challenge to Google. And they show what has been clear for years -- one-time search pioneer Yahoo appears to have thrown in the search towel.

On a month-over-month basis, Microsoft saw the highest gain. "The data was also positive for Microsoft as it continues to take share and, at 9.9%, saw its highest share level since September 2007," Schachter said.

Meanwhile, Yahoo saw its largest month-over-month share decline since August 2008 and at 18.0%, the company's October search share represents its lowest level ever. "For Yahoo, the data was awful," Schachter said.

"Yahoo has ceded share in each of the last nine months, clearly a trend, and a worrisome one at that," the analyst said. "With both Google and Microsoft taking share from Yahoo, it is difficult to pinpoint the reason for the recent share loss acceleration, but Yahoo must find a way to stabilize its share loss or all the effort spent negotiating terms of the search deal will be the least of its worries."