The risk management practices of banks and other big buyers of electricity are under the spotlight, with a couple of them seeking intervention from the energy regulator to compel electricity supplier Genesis to reduce its prices from three weekends ago.ASB and Westpac in New Zealand, along with two dozen other affected big businesses, want NZ's Electricity Authority to compel Genesis Energy to revise its prices.Electricity prices in Auckland skyrocketed to more than 200 times normal levels while Transpower was undertaking planned maintenance between Auckland and the Waikato This significantly reduced the transmission capacity from the Waikato region to Auckland, Interest.co.nz reports.Spot market prices rose to what the Electricity Authority describes as "historically high" interim levels of between NZ$19,000 and NZ$20,000 megawatts per hour -  from the usual price of around NZ$100 MWh.ASB told the Authority that "the financial magnitude of the impact will significantly affect our profitability".Westpac told the Electricity Authority "the financial impact is significant".Both banks, like many other businesses, have elected to buy most of their electricity on the open market, and to manage - or hedge - the risks of price spikes themselves.The two banks are making use of the provisions in the electricity code to assert that the behaviour of Genesis was "unwarranted… or undesirable".