Microsoft has acquired global digital marketing company aQuantive for $6bn (£3.04bn), as the multibillion-dollar landgrab in the internet advertising market continued today.

The acquisition of aQuantive is part of an ambitious Microsoft plan to build a major internet advertising operation and close the gap on rivals such as Yahoo! and Google.

Today's mega-deal dwarfs the $3.1bn (£1.57bn) spent by Google last month acquiring internet ad specialist DoubleClick and the $649m (£329m) deal announced yesterday by WPP to purchase 24/7 Real Media.

Microsoft, which was involved in the bidding for both DoubleClick and 24/7 but ultimately lost out, now intends to build its own global advertising platform based around the aQuantive business.

AQuantive, which is valued at $66.50 per share in the all-cash transaction, owns a range of businesses including interactive ad agency Avenue A/Razor Fish, which in turn owns DNA in London, advertising research company Atlas and online ad firm DRIVEpm.

"Today's announcement represents the next step in the evolution of our ad network from our initial investment in MSN to the broader Microsoft network including Xbox Live, Windows Live and Office Live, and now to the full capacity of the internet," said the Microsoft chief executive, Steve Ballmer.

"The advertising industry is evolving and growing at an incredible pace, moving increasingly toward online and IP-served platforms, which dramatically increases the importance of software for this industry."

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