Gannett Co., Hearst Corp., the New York Times Co. and Tribune Co. are setting up the network as a stand-alone company called quadrantOne. Like a consortium created by Yahoo Inc. and a group of newspapers last year, it will allow national advertisers to buy space on certain Web sites operated by their newspapers in a bid to capture new sales as revenue at their print editions disappear.

QuadrantOne will include more than 120 papers, whose Web sites reach a total of 50 million unique monthly visitors, the company said. All four publishers have devoted funding to the company.

The network doesn’t include Gannett’s largest paper, USA Today, or the New York Times, which already have their own national sales operations. Instead, those companies will use the system to place ads on local titles such as the New York Times’s Boston Globe.

QuadrantOne is designed to let national advertisers buy space in many local papers as well as on the Web sites of local television affiliates, without media buyers and planners having to make calls to multiple companies. If a marketer “can make one phone call to a portal or 100 in local markets to get the same audience” for their product, “the answer…would be a no-brainer,” said quadrantOne interim Chief Executive Dana Hayes.