More electronic commodity contracts traded on exempt commercial markets are helping set market prices than originally imagined - a fact which could subject them to additional regulatory oversight, the head of the federal commodities regulator revealed Wednesday.

Until recently, the U.S. Commodity Futures Trading Commission had more limited oversight authority over contracts traded electronically on exempt commercial markets such as IntercontinentalExchange Inc. (ICE). But when energy prices rose to record highs last year, lawmakers expressed fears that traders were affecting prices by using exempt commercial markets to bypass speculative position limits imposed on similar types of energy futures contracts traded on exchanges.

The 2008 farm bill sought to close this so-called "Enron loophole" by empowering the CFTC to come up with new rules to determine if such contracts were helping to set market prices. If they do serve a "significant price discovery function," then the CFTC must step up its oversight of the contract and impose additional reporting requirements.

The CFTC approved most of those rules earlier this year. Until now, it has been somewhat unclear how many contracts the new rules might impact.

"We were told to look at significant price discovery contracts and we have been doing that," acting CFTC Chairman Michael Dunn said Wednesday, noting that preliminary reports suggest "it was much larger than we originally thought" and that staff was "surprised" by the preliminary findings.

He declined to elaborate, but said more information will be available when it's ready.

-By Sarah N. Lynch, Dow Jones Newswires; 202-862-6634; sarah.lynch@dowjones.com