UPDATE 3-NY Times dissident will not seek re-election

* Board member Galloway will not seek re-election

* Galloway to serve until annual meeting in April (Adds comment from Galloway on Twitter account)

By Sue Zeidler and Robert MacMillan

LOS ANGELES/NEW YORK, Feb 18 (Reuters) - The leader of a 2008 dissident shareholder campaign against The New York Times Co (NYT.N) will not stand for re-election to the company's board.

Scott Galloway, a business and marketing professor at New York University, told the Times board on Wednesday that he will serve until the company's annual meeting on April 27, and the newspaper publisher announced his decision on Thursday.

He declined to tell Reuters why he will quit the board, leaving unanswered the question of whether he was successful at getting the company to change the way it does business.

"Announced I'm leaving board of the New York Times... Bittersweet, great experience," Galloway said in a post on Twitter, the microblogging site that popularized 140-character "tweets" or online messages. "But time to move on."

Galloway spearheaded a campaign financed by hedge fund Harbinger Capital Partners to buy nearly 20 percent of the newspaper publisher's publicly traded shares. At the time, that was a commitment of about half a billion dollars.

Galloway and Harbinger, under fund manager Phil Falcone, wanted the company to shake up its business, something that many U.S. newspaper publishers are trying to do as they search for a sustainable revenue model as advertising sales plunge.

The Times avoided a proxy battle by expanding its board to accommodate Galloway and another Harbinger nominee.

Harbinger's stake lost value as newspaper shares sank during the financial crisis and recession. It also has sold its holdings in recent months.

Its latest reported filing shows its stake at 14.64 percent, which was worth about $230 million based on Thursday's stock closing price of $11.13.

The Times has taken action, since Galloway joined the board in 2008, to improve its balance sheet and stave off high debt payments that were threatening its financial health. Last year it scrapped one of those attempts, giving up plans to sell the money-losing Boston Globe. It still is trying to sell its stake in the Boston Red Sox baseball team.

It also borrowed $250 million from groups controlled by Mexican telecommunications tycoon Carlos Slim, one of the world's richest people.

One of the difficulties that Galloway and Harbinger faced in their battle is the Ochs-Sulzberger family that controls the Times Co through a special class of shares.

The family, which has controlled the Times since 1896, will see one of its members leave the board this year. Daniel Cohen has said that he would step down.

Standing for election is Carolyn D. Greenspon, another family member. Greenspon could not be reached at her home for comment. Her husband declined to comment. (Reporting by Sue Zeidler in Los Angeles and Robert MacMillan in New York; Editing by Phil Berlowitz, Gary Hill)