This excerpt taken from the ATO 10-Q filed Aug 6, 2008.
Natural Gas Marketing Derivative Activities
Our natural gas marketing risk management activities are conducted through AEM. AEM is exposed to risks associated with changes in the market price of natural gas, and we manage our exposure to the risk of natural gas price changes through a combination of physical storage and financial derivatives, including futures, over-the-counter and exchange-traded options and swap contracts with counterparties. AEM uses financial derivatives designated as fair value hedges to offset changes in the fair value of its natural gas inventory and derivatives designated as cash flow hedges to offset anticipated purchases and sales of gas in the future. AEM also utilizes basis swaps and other non-hedge derivative instruments to manage its exposure to market volatility.