It is a conflict of interest which, outsiders argue, enables banks to make huge sums of money on their proprietary trading (dealing on their own account).

ECONOMIST: Investment banks

He joined Goldman Sachs in 2005 and worked there until his sacking, for building up "inappropriately large proprietary futures positions in a firm trading account", according to a filing with the Financial Industry Regulatory Authority (Finra).

BBC: Former Goldman Sachs trader pleads guilty to wire fraud

Goldman fired Mr. Taylor on Dec. 21, 2007, for "alleged conduct related to inappropriately large proprietary futures positions in a firm trading account, " the bank wrote in a filing submitted to the Financial Industry Regulatory Authority, which oversees broker-dealers.

WSJ: Ex-Goldman Trader Pleads Guilty to Fraud

Don't be surprised if the administration pushes for the controversy over commercial banks' handling of derivatives trading to be addressed by the so-called "Volcker Rule, " which would prohibit commercial banks from making speculative bets for their own account--known as proprietary trading--as opposed to the benefit of their customers.

FORBES: Intelligent Investing Briefing Book