A former chief executive of Optionable Inc. commodities brokerage was sentenced to prison for a term of 2-1/2 years on Wednesday for his role in defrauding the Bank of Montreal.  He was found guilty of helping to inflate the value of the bank's natural gas derivatives portfolio. In August 2011, the former Optionable executive, Kevin Cassidy, of Bedford Hills, NY, pleaded guilty to one count of conspiracy to commit wire fraud in Manhattan federal court.  Cassidy was charged in November 2008 with six felony counts. In addition to the 30 months in prison (2-1/2 years), U.S. District Judge Thomas Griesa order Cassidy to 3 years of supervised release - to begin after he leaves prison. The judge also ordered Cassidy to forfeit $200K, according to federal prosecutors. Details of the Case. Prosecutors had accused Cassidy of helping David Lee, Bank of Montreal's former lead commodities trader, inflate the fair market value of natural gas options positions in his derivatives trading portfolio from 2004 to 2007.  In return, Lee allegedly funneled trades to Cassidy, resulting in Bank of Montreal generating more than 40% of Optionable's brokerage revenue by early 2007. Lee pleaded guilty in November 2008 and is awaiting sentencing. When the scheme unraveled, Bank of Montreal stopped doing business with Optionable, causing the brokerage's shares to plunge after a more than sixfold gain in less than 2 years. Lee's trading contributed to a C$853 million loss in BOM's commodities trading business for 2007. The case is: USA v. Cassidy in U.S. District Court for the Southern District of New York, No. 11-01101. Representing USA: Jillian Berman of the U.S. Attorney's Office Representing Cassidy: Douglas Jensen of Park & Jensen For further details, go to:  [Reuters, 4/25/12].