Sept. 4 (Bloomberg) -- The New York Sun, the six-year-old newspaper funded by Bruce Kovner and Michael Steinhardt, may close by the end of the month if it can't raise ``tens of millions'' of dollars to cover losses, its top editor said.

The Sun, begun as an alternative to the New York Times, has never made money, editor Seth Lipsky wrote in a letter to readers posted on the company's Web site yesterday. While the original backers are ready to put in more cash, the losses require the Sun to broaden its base of investors, he said.

The Sun has been caught in one of the nation's only newspaper wars, slugging it out with the Times, New York's tabloids, free-circulation dailies and the Wall Street Journal for advertisers and readers, Lipsky said in an interview.

``No one in the war is making much money on their New York circulation, but they're all hanging in,'' Lipsky said. ``The winner has a tremendous upside potential.''

Lipsky wouldn't disclose the size of the Sun's losses or say who the Sun had approached for more funding. He said the money needed would cover a ``medium-term business plan.''

The Sun has boosted print advertising in recent years, he said. The five-day-a-week newspaper has a print readership of 113,000, focused on ``affluent, educated'' New Yorkers, and 2 million monthly Internet visitors, according to its media kit for advertisers.

Kovner is chairman of the hedge fund firm Caxton Associates LLC, and Steinhardt is the chairman of Steinhardt Management Co. Former Hollinger International Inc. Chief Executive Officer Conrad Black also invested the company's money in the Sun at its founding. Lipsky said Hollinger sold its interest before Black was convicted of fraud last year.

Lipsky, a former managing editor of the Asian Wall Street Journal and editor of the Jewish newspaper the Forward, hasn't considered what he might do if the newspaper closes, he said. He's married to Amity Shlaes, a columnist for Bloomberg News, which is owned by Bloomberg LP.

The possibility that the Sun would close was earlier reported yesterday by the Wall Street Journal.

To contact the reporter on this story: Tim Mullaney in New York at tmullaney1@bloomberg.net

Last Updated: September 4, 2008 11:27 EDT