Mark Carney, governor of the Bank of Canada and chairman of the Financial Stability Board, said the Volcker rule could hinder market efficiency. "I am speaking from my perspective at the Bank of Canada," Carney said. "We and other officials in Canada have looked at the current draft of the Volcker rule, and we have some obvious concerns." Carney said there is a risk that the rule will prevent banks from purchasing securities as they conduct trades for customers. "It is not clear the definition of 'market making' versus 'proprietary trade'," he said.