We provided forensic accounting analysis to uncover a rogue trader’s methodology for fraudulently manipulating trading accounts of an options clearing broker in connection with a Chicago Board Options Exchange (CBOE) arbitration matter. The trader circumvented controls and issued false account statements to his investors based on his commingling of assets between his own accounts and those of his investors. We analyzed five years of options and equity securities trading documents and data, back-office accounting records of the clearing broker, and the trader’s alleged hedged risk and trading strategies. We reconstructed the profit and loss statements for the trader’s nine subaccounts and his consolidated account net of the fraudulent manipulation.