Google's shares have climbed 8% after hours on news the search giant is defying the slump. Yahoo zoomed 15% following comments by Microsoft CEO Steve Ballmer that his company acquiring Yahoo "would make economic sense".

For Q3, Google's profit rose 35% to 1.35 billion on revenue that was up 39% to $US5.54 billion.

However, the company has already put the brakes on, says CEO Eric Schmidt, as the global economy enters what he says is "uncharted territory".