The energy watchdog has also accused four of its traders including Daniel Brin, Scott Connelly, Karen Levine, and Ryan Smith, for changing power prices in order to make profits in related positions in the swaps market during late 2006 to 2008.
The regulator has also sent a show cause notice to the traders as well as the bank, to respond and prove themselves within 30 days.
The bank has however, denied the allegations and said that the order seems to be "by nature a one-sided document, and does not reflect a balanced and full description of the facts."
Barclays spokesman Mark Lane told Business Standard, "We believe that our trading was legitimate and in compliance with applicable law."
"We have cooperated fully with the FERC investigation, which relates to trading activity that occurred several years ago. We intend to vigorously defend this matter."
The FERC has sought for $34.9m in ill gotten gains with interest, in addition to a $435m civil penalty.
