These sources said that the account, which has been closed, was very active and had a good deal of suspicious trading.

PIR was the service that first reported the story about suspicious trading on the information in Business Week.

They are accused of making about $8.2 million from the "highly suspicious" trading of Dow Jones stock.

In addition, the suspicious trading could raise new questions about why Dow Jones did not disclose the Murdoch offer earlier.

The account was suspended after the suspicious trading was discovered.

Without a pattern of suspicious trading, he said, the magazine saw no need to inform the various agencies.

Triton's president, Michael Earley, said in an interview that he would not be surprised if his inquiry discovered no suspicious trading.

He quickly adds that none of the suspicious trading involved accounts held at the firm and that there is a clear firm policy against front-running.

The S.E.C. will not say whether it is investigating these or any other recent episodes of suspicious trading.

Still, no whistles were blown, although a code of best practices for the foreign exchange market suggests that suspicious trading should be reported.