WASHINGTON — Information may be power, but collecting too much of it could cause Google Inc. trouble.
The Internet search leader said Tuesday that the Federal Trade Commission had launched an antitrust review of its plan to buy DoubleClick Inc., an online advertising firm, for $3.1 billion. The FTC gave Google a detailed list of questions about the deal's potential effect.
Concerned about the implications of marrying Google's vast amount of consumer information with that collected by DoubleClick, public interest groups have pressed the agency to review the deal.
Google rivals including Microsoft Corp. also have asked federal regulators to block the deal, saying it would hamper competition in the booming online advertising industry.
The FTC's decision to seek more information from the companies after a standard initial review doesn't necessarily mean the deal is in trouble. The agency often asks tough questions, then approves a deal with few or no conditions.
But some analysts and privacy advocates said Google's accrual of data could factor into the FTC's decision about whether the deal would hurt competition.
The big question facing Google: By using DoubleClick's technology to collect even more detailed information about how millions of people use the Web, would the world's biggest online marketer make life even more difficult for its competitors?
"The privacy issue is also the competitive issue," said Blair Levin, an analyst at brokerage Stifel, Nicolaus & Co., who expects the FTC to approve the purchase. "The biggest barrier to entry is not money or engineers or the networks but the information on the behavior of people on the Internet."
Google executives have said the online advertising industry is healthy and fast-changing. Since the deal was announced last month, other big online-ad acquisitions have buoyed the industry, including Microsoft's $6-billion deal with AQuantive Inc.
"We are confident that upon further review the FTC will conclude that this acquisition poses no risk to competition and should be approved," Don Harrison, Google's senior corporate counsel, said Tuesday.
But the FTC review comes amid growing concern about Google's online dominance. Last week a European Union panel said it was looking into whether Google's retention of search data complied with European privacy rules. Google keeps the data indefinitely, but it said in March that it would soon begin removing personally identifiable information from the search queries it collects after 18 to 24 months.
