Like the last unattached cheerleaders, in the week before prom, independent advertising companies are going fast. This morning's big news: Microsoft is taking out the biggest of them all , Aquantive, the group which owns media buyer Avenue A, web shop Razorfish, and other pieces of the online advertising puzzle. The deal, at $6bn, a huge premium to Aquantive's share price, brings the recent acquisition spree in the interactive market to a gigantic $10bn. The orgy of takeovers illustrated after the jump, which have all taken place in the last month, is most frenzied since the last bubble. Microsoft's deal for Aquantive, twice as expensive as Google's purchase of Doubleclick, makes sense geographically, because Aquantive's business is based in Seattle, the software giant's home. The strategic rationale is less clear. More about that later.

[In the chart, on the x-axis, the market value of the acquirer. The size of the transactions are shown on the y-axis, and by the size of the bubble.]