CHICAGO — An investor group led by former Chicago alderman Edwin Eisendrath and the Chicago Federation of Labor on Wednesday bought the Chicago Sun-Times, keeping the city’s No. 2 paper in business and ending a bid by the Chicago Tribune’s owner to acquire its longtime rival.

The sale of the Sun-Times by its owner, Wrapports, followed two months of negotiations, public pitches for bidders and close guidance from federal antitrust regulators. Sources familiar with the deal put the price tag at $1, or the cost of a single copy of the storied tabloid.

“We’ve closed,” said Eisendrath, 59. “I’m very grateful to everyone who made it possible to save this independent news voice in Chicago.”

With the Sun-Times losing about $4.5 million per year, the purchase still could prove to be expensive for the new owners. Eisendrath said he would have more to say about his plans for the newspaper at a Thursday news conference.

In addition to union backing, Eisendrath’s group includes corporate turnaround specialist Bill Brandt and a handful of unnamed Chicago investors who pooled the required $11.2 million needed to fund the newspaper’s projected losses over the next 30 months, according to Brad Bulkley, a financial adviser to Wrapports in the sale.

“We were trying to maximize value, but an equally important objective was to keep the paper published,” Bulkley said Wednesday.

Chicago-based Tronc, which owns the Tribune, Los Angeles Times and seven other major newspapers, announced May 15 that it had entered into a nonbinding letter of intent to acquire Wrapports – whose properties include the Sun-Times and the Chicago Reader – for an undisclosed price. The Sun-Times is obligated by a $25 million annual printing and distribution contract with the Chicago Tribune through 2019.

While Tronc pledged that the 69-year-old Sun-Times would remain an independent news operation, the Justice Department intervened, seeking to preserve competition through separate ownership.

Wrapports published notice of the proposed sale to Tronc and solicited competitive bidders May 16, posting in the Sun-Times that it was seeking a buyer “that will agree to publish the newspaper.” According to the terms of the deal, if no other “viable buyer” emerged within 15 days, the Sun-Times would be sold to Tronc.

At the behest of the Justice Department, the deadline was extended several times to accommodate potential buyers until Eisendrath’s group submitted its bid June 19.

“Tronc has always been committed to keeping the Sun-Times an independent media voice within the city of Chicago,” Tim Knight, president of TroncX, the digital division of Tronc, said in a statement.

“We’re pleased to see that happen and we look forward to the new owners honoring our contractual agreement for printing and distribution services under the terms of our multi-year agreement. Tronc will move ahead to execute our growth strategy, leverage technology and increase the digital audience of our award winning journalistic brands.”

In a statement, the Justice Department said that as a result of the sale to the investor group, the agency will close its investigation of Tronc’s possible acquisition of the Sun-Times.