BBC News 10 December 2013 Last updated at 15:01 ET
All five US financial regulators have approved the Volcker rule, designed to restrict the finance industry in the wake of the 2008-09 financial collapse.
Named after former Federal Reserve chairman Paul Volcker, it bans banks from using their own funds for trading activities.
It is considered the centrepiece of the 2010 banking reform legislation known as Dodd-Frank.
Banks will have until 21 July 2015 to comply with the rules.
The five agencies ruling on the measure are: the Federal Reserve, the Federal Deposit Insurance Corporation, the Office of the Comptroller of the Currency,...