Memberships in Chicago's exclusive futures exchanges are selling at record high prices as the federal investigation into alleged fraudulent trading has faded from the headlines.

At the Chicago Mercantile Exchange, the world's second-largest after the nearby Chicago Board of Trade, two full memberships sold last month for a record $550,000 each, a reflection of the strength and optimism in the markets.This was in contrast to just over three months ago, when fear and suspicion swept through the pits as the existence of federal undercover agents disguised as traders came to light.

But some lawyers with knowledge of the probe say the investigation may have become mired in the complexities of the arcane world of futures trading, and that has made indictments slow to emerge from the grand jury.

Meanwhile, booming trade in the CME's Eurodollar and currency futures pits, where highly leveraged contracts representing the future cost of interest or the relative value of West German marks or Japanese yen to the dollar change hands in a flurry of hand-signals, have led the recent surge in seat prices.

At the Chicago Board of Trade, where federal agents wearing microphones under their trading jackets reportedly gained the trust of brokers, seat prices have stabilized.

The last sale was for $410,000, still well below the $550,000 paid during the summer drought when grain prices were rocketing upward and profit potential was at a peak.

Conversations among grain traders that once focused on whom federal agents would target for skimming customers now revolves around the chances of another year of dry weather.

The exchanges themselves are actively pursuing wrong-doers, using their self-policing powers to mete out fines and suspensions to offending traders.

On Thursday, Robert Abrams, a broker in the CME's popular Eurodollar futures pit, was fined $25,000 and suspended for 20 trading days for pre-arranging transactions with a local trader, Brett Burkholder.

Burkholder, a former college basketball player whose height works to his advantage in the tumultuous pit, was fined $15,000 and suspended for 10 days.

At the Board of Trade, one trader was fined a modest $500 for using "obscene and abusive language."