U.S. federal energy regulators threatened to fine Barclays roughly $470 million to settle allegations that the bank and its traders manipulated California energy markets from November 2006 to December 2008.
The U.S. Federal Energy Regulatory Commission said in an order issued on Wednesday that Barclays has 30 days to show why they should not be penalized.
FERC also said four of the company's power traders - Daniel Brin, Scott Connelly, Karen Levine, and Ryan Smith - have 30 days to show why they should not be assessed a total of $18 million in civil penalties.
The FERC Office of Enforcement staff alleged Barclays engaged in a coordinated scheme to manipulate trading at four electricity trading points in the Western United States.
Specifically, Office of Enforcement staff allege that "Barclays engaged in loss-generating trading of next-day fixed-price physical electricity on the IntercontinentalExchange at the locations of Mid-Columbia, Palo Verde, South Path 15 and North Path 15 to benefit Barclays' financial swap positions in those markets".
(Reporting by Scott DiSavino and Karey Wutkowski; Editing by Gary Hill and Andrew Hay)