US crude prices plunged on OPEC's decision to not cut output, but light trading on Friday after the U.S. Thanksgiving Day holiday meant there could be more losses when markets return to full strength next week, traders said.
U.S. crude's front-month contract closed $7.54, or 10.2 percent, lower at $66.15 per barrel—its lowest settlement since September 2009.
The front month for benchmark North Sea Brent crude fell about $2 to $70.45, its lowest since July 2010.
West Texas Intermediate (WTI) light U.S. crude hit fresh lows after Saudi Arabia blocked calls on Thursday from poorer members of the Organization of the Petroleum Exporting Countries to reduce production. U.S. markets were officially closed on Thursday for Thanksgiving, with only electronic trading.
Traders said if WTI takes out the May 2010 low of $64.24, it could technically be headed for a test below $60, toward the low of $58.32 set on July 2009.
``There's a notion that yesterday's selling was overdone, but not everyone is fully back to work yet after Thanksgiving,'' said John Kilduff, partner at energy hedge fund Again Capital in New York. ``WTI could certainly be down a couple of dollars more next week, and test newer lows from there.''