NEW YORK (AP) – The New York Times Co. said Wednesday that advertising revenue dropped 20.9 percent in November from a year ago, as the financial crisis prompted steep declines in classified and national ad spending.

The sharp economic deterioration, which followed the turmoil in the financial markets this September, has exacerbated an already-weak advertising market for newspapers as readers and advertisers have migrated to the Internet.

As part of its efforts to shore up its core assets amid the slump, the Times Co. is actively seeking buyers for its 17.5 percent stake in the holding company of the Boston Red Sox, The Wall Street Journal reported Wednesday. New England Sports Ventures owns the baseball club, Fenway Park and a majority interest in the New England Sports Network.

The Journal cited an estimate by Barclays Capital that the Times Co. stake in NESV could be worth about $166 million. Times spokesmen were not immediately available to comment on the Journal report.

The Times Co.’s ad revenue, which makes up nearly two-thirds of total revenue, had booked declines of 16.2 percent in October and 14.1 percent in September.

Total revenue from continuing operations fell 13.9 percent last month.

For The New York Times’ news media segment, advertising revenue dropped 21.8 percent, while circulation revenue grew 4.2 percent. At its flagship newspaper, the New York-based company said weakness in the studio entertainment, national automotive, book and financial-services categories drove declines in national ad spending. Classified ad revenue in the segment also plunged 33.3 percent.

Total Internet revenue – which also includes NYTimes.com, About.com and other company-owned Web sites – dipped 2.6 percent in November. In total, Internet businesses accounted for 12.1 percent of total revenue in November, up from 10.7 percent in November 2007.

The company noted that Internet revenue gained 8.3 percent over the year-to-date period.

The New York Times said unique visitors in the U.S. rose 11 percent to 55 million from 49.6 million unique visitors in November 2007, according to Nielsen Online. The company had the 10th largest presence on the Web and NYTimes.com maintained its position as the top newspaper Web site in the U.S.

AP-ES-12-24-08 1941EST