Microsoft has today announced a £3million ($6 billion) deal to buy online marketing outfit Aquantive in its biggest ever takeover. The deal follows Google's recent $1.5 billion acquisition of online ad agency DoubleClick as Microsoft does what it can to minimise Google's dominance of the online ad market.

Earlier this week Aquantive told Reuters that it would not be challenging the Google/DoubleClick deal on the basis of lesser competition. "I feel confident it will be looked at and addressed by the government," Aquantive chief executive Brian McAndrews said in an investor conference call with investors.

"We're not challenging the deal. There are people with deeper pockets than us that have expressed interest."

We wonder quite who he could have been talking about. Microsoft's acquisition of Aquantive is an all-cash deal which is 85 per cent higher in value than its closing share price yesterday.

Microsoft says the price is worth it to acquire the technology that Aquantive uses. "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," said Steve Ballmer, chief executive officer of Microsoft.

Ballmer also said that the fruits of the acquisition would sit alongside the corporation's existing web services.

"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."