The Federal Trade Commission could be the latest agency to investigate the search leader, which has already come under scrutiny in Texas and in the EU.
The Federal Trade Commission is considering a broad antitrust probe of search giant Google, a published report said Tuesday.
Citing two sources it said were familiar with the FTC's plans, Bloomberg said the Commission is growing increasingly concerned about the extent to which Google dominates Internet search and related services, such as search-based advertising.
Before taking any action, the FTC will wait until the Department of Justice decides whether to challenge Google's $700 million acquisition of ITA Software, a move that could limit competition in travel-related search, Bloomberg reported.
Officials from Google and the FTC did not immediately respond to a request for comment.
Word of the possible probe comes amid increasing scrutiny of Google's operations. Texas attorney general Greg Abbott launched an antitrust investigation into the company late last year. Just last week, Microsoft said it would join an antitrust action against Google that was recently filed with the European Union by a number of smaller search companies. The suit accuses Google of using commercial and technical means, such as proprietary ad formats, to limit search competition on the Continent.
"We're concerned by a broadening pattern of conduct aimed at stopping anyone else from creating a competitive alternative," said Brad Smith, general counsel at Microsoft, in a statement.
The latest data from Comscore shows the combined U.S. market share in search for Microsoft and its partner Yahoo, which hands off queries to Microsoft's Bing search engine, is less than half of Google's. Google holds 65.4% of the market, while Microsoft and Yahoo sites together hold 29.7%. Microsoft on its own holds just 13.6%.
Google is also fast becoming the dominant player in mobile operating systems. IDC expects Google's Android OS to grab 39.5% of the worldwide market this year, compared to just 20.9% for number two player Symbian.
Whether it's all enough to draw the FTC into the fray remains to be seen. FTC commissioner J. Thomas Rosch recently told the political blog Politico that he's worried that the largest Internet companies are dominating smaller rivals, and mentioned Google by name. On the other hand, the FTC last year gave Google the green light to acquire mobile advertising specialist AdMob, after concluding that the move would not limit competition in the mobile ad market.
Google shares were down 2.77%, to $571.41, in midday trading Tuesday on investors' concerns that a prolonged FTC investigation could hamper the company's growth.