Several energy companies moved to distance themselves from the cloud of scandal gathering at trading desks that carried out profitless power transactions to artificially inflate volumes.




El Paso Corp.





all said they didn't engage in so-called wash or round-trip energy trading while

Williams Cos.

(WMB) - Get Report

said such trades made up less than 1% of its total trading volume over the last two years and didn't affect revenue.

The trades, which are legal but have the effect of meaninglessly inflating trading volumes and sometimes revenue, have recently come to light at




Reliant Resources



CMS Energy

(CMS) - Get Report

, sending their respective stock prices into tailspins and subverting confidence in the U.S. energy markets.

Williams said the trades "didn't add a nickel to our revenues," adding: "Even though the number of trades we've found with these characteristics is extremely small, the very nature of reporting on a net basis means that they are not included in our reported revenues."

The company said it's still working to complete a review of its energy trading practices in California following an inquiry from the Federal Energy Regulatory Commission. The commission is investigating what role other energy companies might have had in various trading strategies carried out by


. Williams said it will make its response on Wednesday.