Edward Cox, owner of Cox Securities, the largest floor broker on the Pacific Exchange, was suspended from the exchange as part of an investigation into the company's record and bookkeeping practices, officials at the exchange said. "We have an internal investigation going," said Dale Carlson, spokesman for the Pacific Exchange. "There's no fraud, no front-running, no market manipulation," he added. Cox and his firm were suspended indefinitely by the executive committee of the board of governors of the exchange, Carlson said. Though Cox is the largest floor broker at the PCX in Los Angeles, it actually represents a small percentage of the exchange's volume, because more than 95% of all trades are now done electronically, Carlson said. Cox made trades mostly for institutions. Cox has no record of previous disciplines or fines, according to the National Assn. of Securities Dealers. Attempts to reach Cox were not successful.