The US Department of the Treasury wants a single version of the Volcker rule – the Dodd-Frank Act's limits on proprietary trading and private equity investment by US banks – according to Mary John Miller, its under-secretary for domestic finance, who was speaking at an Institute of International Bankers (IIB) conference in Washington, DC today. That will require co-ordination and agreement between the five federal regulators charged with writing it, she said.

"We think a joint rule is optimal. To have a different rule developed by a banking regulator and a securities regulator would not be helpful to the market...