The world's largest futures exchanges are in the middle of an unaccustomed kind of speculation, featuring not the price of wheat or bonds but allegations of fraud and a possible brush with organized crime.

Traders, brokers and others who work at the Chicago Board of Trade and the Chicago Mercantile Exchange expressed hope on Friday, as the exchanges closed for the weekend, that the full extent of a government investigation into their operations would soon be made public.Some said they feared the continuing uncertainty could dampen business. The probe has already deflated prices of seats on both exchanges, where one seat sold on Friday for $40,000 less than the asking price just two weeks earlier.

Officially, the investigation is still a secret. U.S. Attorney Anton Valukis told Reuters on Friday: "I can say nothing."

But sources close to the investigation have said FBI agents who posed as traders found massive amounts of fraud on both exchanges in which traders and brokers cheated their customers and each other out of millions of dollars.

In addition, a source close to the investigation told Reuters that FBI agents believe organized crime used the floor of the Chicago Mercantile Exchange to launder illegal profits from criminal activity.

The source said relatives of organized crime figures have worked at the Mercantile Exchange in positions where they could launder money.

A spokesman for that exchange called the organized crime report "unfounded and irresponsible."

The Mercantile Exchange also denied broadcast and newspaper reports that its firms or officers had been subpoenaed, saying:

"Rumors and reports concerning subpoenas being issued to the firms or officers of the exchange are unfounded and irresponsible. We do not believe that any of our firms are implicated in any wrongdoing."