Conde Nast CEO Charles Townsend said Monday he was shutting down four magazines, including the awarding winning Gourmet, parenthood title Cookie and two of the company’s bridal magazines, Modern Bride and Elegant Bride.

It was the biggest one-day bloodbath in the publishing company’s 100-year history. Hundreds of people will be tossed out of work.

The company said it would keep the Gourmet cookbooks and television programming but shut the monthly magazine. Bride’s, the last surviving bridal book, will move to monthly from six times a year.

Industry sources had estimated that Conde Nast could lose $200 million this year.

The closings come after the management consulting firm McKinsey & Co. completed a three-month study of the American magazine publishing giant that is headed by billionaire chairman S.I. Newhouse, Jr., and is part of his family’s Advance Publications empire.

In the memo released to staffers this morning, Townsend said:

“We have now completed an extensive review of our business — an important undertaking given the dramatic changes in the U.S. economy. The review has led us to a number of decisions designed to navigate the company through the economic downturn and to position us to take advantage of coming opportunities.

“Condé Nast’s success comes from the ability of our publications to attract readers with a wide range of interests, as well as advertisers who value them. But in this economic climate it is important to narrow our focus to titles with the greatest prospects for long-term growth.”