FTC scrutinizes Google's acquirement of DoubleClick

The inquiry began at the end of last week, after it was decided that the Federal Trade Commission instead of the Justice Department would conduct the review, said the executive, who asked not to be identified because he had not been authorized to speak. The two agencies split the duties of antitrust enforcement.

An FTC spokesman said Monday that the agency did not comment on pending inquiries.

The deal, involving powerful forces in their respective niches of the online advertising business, prompted privacy advocates and competitors to raise concerns after it was announced last month. Those concerns and the deal's size made a preliminary investigation all but certain, according to antitrust experts.

Within a few weeks, perhaps within days, the FTC will decide whether to escalate its investigation into the Google deal, antitrust experts say. That step, known as a "second request" for information, would suggest that the proposed acquisition raises more serious antitrust issues.