Barclays and four of its traders have been hit with a $453m (£299m) fine by the US electricity regulator for fixing power prices.
The Federal Energy Regulatory Commission has accused Barclays traders of manipulating physical power prices in California and other western US states in order to fraudulently boost financial derivative positions.
Barclays has been ordered to pay $435m in penalties, while one of its traders must pay a $15m fine and three other traders $1m each. The bank must also hand over $34.9m in profits which will be given to low-income homeowners in California, Arizona, Oregon and Washington to help them pay their energy bills.
A statement from Barclays says: “We believe that our trading was legitimate and in compliance with applicable law.
“The Order Assessing Civil Penalty is by its very nature a one-sided document, and does not reflect a balanced and full description of the facts or the applicable legal standard.”
It is not the first time Barclays has been in regulatory hot water. Last year, the bank was fined a total of £290m over its role in the manipulation of Libor.
The FSA fined Barclays £59.5m for manipulating Libor and the Euro Interbank Offered Rate, while US regulators the US Commodity Futures Trading Commission and the US Department of Justice fined Barclays £230.5m for the same offences.