"Round-trip" trades are simultaneous, pre-arranged trades of energy with a counter-party, at the same price and volume, and over the same term, resulting in neither profit nor loss to either transacting party.
It came a day after a judge at the Federal Energy Regulatory Commission ruled that affiliates of Dynegy's cross-town rival, El Paso, illegally squeezed the supply of natural gas to California during its energy crisis.
The SEC said it had found that Dynegy engaged in securities fraud in connection with its disclosures and accounting for Project Alpha, a $300m financing transaction, and negligently included materially misleading information about round-trip trades in two press releases in early 2002.
Dynegy isn’t the only company in this case, several other energy traders remain under investigation for similar trades aimed at boosting volumes and revenue.
Dynegy's shares closed up 2.5 per cent at $1.20. El Paso's shares closed down 30 per cent at $5.30.