PORTLAND — Guy Gannett Communications, whose holdings include seven television stations and four Maine newspapers, is up for sale.

Employees of the family-owned media business were told Tuesday of the sale, which is expected to be concluded by year’s end, company officials said. Guy Gannett Communications, which is not related to Gannett Co. Inc., runs three daily newspapers, the Portland Press Herald, the Kennebec Journal in Augusta and the Central Maine Morning Sentinal in Waterville, as well as the Maine Sunday Telegram and a Bath weekly, the Coastal Journal.

Begun in 1921, the company is held under a family trust controlled by Madeleine G. Corson, 60, granddaughter of company founder Guy P. Gannett, and by her uncle John H. Gannett, 78.

The decision to sell came last Wednesday, a company spokesman said, and was based on options developed by a special committee established by the company’s board in December.

The trust expires when Corson and Gannett die, and company officials said that by selling now, the family has a better chance of influencing to whom it is sold.

“At some point [the sale] is inevitable, but do you wait and let nature take its course and be faced with all the uncertainty, or do you decide the fate of the company when the company is strong and healthy and you’re in a position to determine to whom and when it is sold?” said Ted O’Meara, director of communications for Guy Gannett.

Selling prices for media outlets are high these days, said O’Meara, who is optimistic that the company will have a prospective buyer within the next three to four months.

O’Meara’s confidence in a seller’s market is shared by media analyst John Morton of Morton Research Inc. in Silver Spring, Md.

Prices for media outlets are at a peak and have been for the last few years, Morton said late Tuesday afternoon. Last year alone, 162 daily newspapers changed hands, up 37 percent from the year before.

In Guy Gannett, a buyer has a ready-made cluster of newspapers, he said.

“If a family is deciding whether to sell a newspaper, now’s the time to do it,” Morton said.

Just how much will the sale be worth? Guy Gannett is a privately held company and O’Meara said figures on profits and company worth were unavailable.

Morton estimated that the newpaper end of the operations alone is worth about $120 million to $150 million, but an estimate for the value of the seven television stations, only one of which is in Maine, was more difficult to come by.

Guy Gannett is opening the sale to public and private companies and has hired Lazard Freres & Co. in New York to assist in the sale. The company could look at selling the company as a whole or in pieces, O’Meara said, although Morton said it likely that the company would be sold as a package.

With the complete package, however, the new owner would have to divest either the Portland newspaper or the Portland television station WGME-TV because of federal prohibitions on media ownership in a single market. Guy Gannett was grandfathered and thus exempt from this requirement.

As well as its newspaper operations, Guy Gannett also runs television stations WICS-TV in Springfield, Ill; WICD-TV, in Champaign, Ill.; KGAN-TV in Cedar Rapids, Iowa; WGGB-TV in Springfield, Mass.; WOKR-TV in Rochester, N.Y.; and WTWC-TV in Tallahassee, Fla.