The folks over at Cablevision may be suffering some serious buyer’s remorse this week — to the tune of $450 million. The company, which purchased Long Island-based Newsday last July from Sam Zell‘s struggling Tribune Co. announced yesterday that it plans to write down its newspaper assets by “between $375 million and $450 million.” Ouch. Per today’s New York Post:

Cablevision admitted as much in its filing, saying the pre-tax charges “reflect the continuing deterioration of values in the newspaper industry and the greater-than-anticipated economic downturn” that has hurt the paper’s advertising business.

In writing down the value of Newsday Media Group, Cablevision is wiping out nearly 70 percent of what it paid for newspaper assets. The company said the charges will be included in 2008 financial results, but will not result in any material future cash outlays.