The impact of the proposed merger of Microsoft and Yahoo’s search platforms raises "significant antitrust concerns" that include the impact on the Yahoo Newspaper Consortium, four groups argue in a letter Monday to the U.S. Justice Department Antitrust Division.

"How will the transaction impact the operation of Yahoo’s Newspaper Consortium, which now serves as a revenue source for the beleaguered newspaper industry?," asks the letter to Assistant Attorney General Christine Varney from the four groups: the Center for Digital Democracy, Consumer Action, Consumer Watchdog and U.S. PIRG (Public Interest Research Group).

"The specter of a joint Yahoo and Microsoft-operated Consortium must be evaluated as well for its potential impact on other online publishers," the letter adds.

The groups have raised alarms in the past about behaviorally targeted ads, which are one of the tools that has been developed by Yahoo for the Newspaper Consortium members.

"Both Microsoft and Yahoo have created elaborate data collection services across various platforms and applications, including sophisticated behavioral targeting systems that raise profound competitive and privacy concerns," the letter states. "We urge the DOJ [Department of Justice] to work closely with the Federal Trade Commission so that agency can address the consumer privacy issues raised by this proposed deal."

If Microsoft, in effect, takes over Yahoo’s search platform, the letter asks, is that "simply a precursor to the eventual absorption by Microsoft of Yahoo’s various advertising holdings, including search and display marketing, ad exchanges, mobile campaigns, and interactive advertising research and development?"

The letter asks the antitrust division to investigate whether the "combination and integration of two powerful sets of data-collection, profiling and targeting technologies, will this proposed entity be able to unfairly leverage its online ad apparatus to place competitors at a disadvantage."