Microsoft, AT&T, Yahoo and AOL were among the voices protesting the $3.1 billion acquisition of DoubleClick by Google, reports the Financial Times.

Microsoft pointed out in a statement that the deal would have 80 percent of the publisher-delivered online ads running through one door. AT&T says it shuts any other player out of hoping for significant ad revenue. Yahoo and AOL reportedly expressed the same sort of frustration and concern.

Not only does the sheer scale of the deal make it a target for anti-trust concerns, but increased information collection could add to that. Google said it will start delivering tracking cookies to user's computers, a practice it had long avoided. Now, it says, DoubleClick's system will allow the cookies to increase ad relevancy. Collecting more data, though, adds to worries of one company compiling profiles of internet users against their wishes.

DoubleClick itself backed down from such collection a couple years ago after it became the major target of privacy activists and several congressional committee hearings.