(125)The G20 summit in Pittsburgh on 25 September 2009 agreed to improve the regulation, functioning and transparency of financial and commodity markets to address excessive commodity price volatility. The Commission Communications of 28 October 2009 on ‘A Better Functioning Food Supply Chain in Europe’, and of 2 February 2011 on ‘Tackling the Challenges in Commodity Markets and Raw Materials’ outlined measures that fall to be taken in the context of the review of Directive 2004/39/EC. In September 2011, the International Organization of Securities Commissions published Principles for the Regulation and Supervision of Commodity Derivatives Markets. Those principles were endorsed by the G20 summit in Cannes on 4 November 2011 which called for market regulators to have formal position management powers, including the power to set ex ante position limits as appropriate.