A man convicted of masterminding a scheme in which a trader wore disguises to make deals in the trading pits has been fined a record $1.125 million and banned for life from the Chicago Board of Trade.

The commodity exchange's decision, disclosed late last week, came four months after the man, Thompson Sanders, was sentenced to six years in prison and fined $300,000 for making illegal transactions in the Treasury Bond pit.At the time, U.S. District Judge Marvin Aspen said Sanders' crimes represented "the tip of the iceberg" and that because of loose regulations, the Board of Trade was a potential "cesspool" of corruption.

The Board of Trade's fine on Sanders was the heaviest it has ever imposed.