The Securities and Exchange Commission is investigating unusual movements in stocks prior to their mention in upcoming issues of Business Week, the magazine's publisher confirmed.

Mary McGeachy, a spokeswoman for McGraw-Hill Inc., said the company was cooperating with the SEC, which is being joined in the probe by the New York Stock Exchange.According to The Wall Street Journal, the American Stock Exchange and the National Association of Securities Dealers are also participating, but McGeachy could not confirm that claim.

Late last week the publishing company confirmed that its legal counsel was investigating suspicious price movements and heavy trading in stocks mentioned in the "Inside Wall Street" column before Business Week was available to the public.

While the investigation encompasses McGraw-Hill's entire operation, some magazine officials believe the information was leaked by someone unrelated to the editorial staff, such as a printer at one of the four plants where Business Week is printed, or a postal worker.

The magazine's 960,000 circulation weekly issue is printed early Thursday and is released to the press after the market closes that day and to the general public on Friday.

Experts had expected McGraw-Hill to team up with the enforcement operations of stock exchanges and the SEC to trace the leak.

McGeachy said the magazine plans to include a statement on the stock activity in this week's issue, due to reach the public on Friday. The statement is expected to confirm that Business Week is conducting its own investigation as well as cooperating with authorities.

In addition, the statement notes that the magazine's already "stringent" internal securities measures have been beefed up.