U.S. crude tumbled 10 percent in its biggest one-day drop in more than five years on Friday, and benchmark Brent broke below $70 a barrel, as OPEC's decision not to cut output sent oil traders and analysts scurrying to find a new trading floor.
"I see little reason to buy oil now. I think people are either going to drive it down further or just let the market collapse," said Tariq Zahir, managing member at Tyche Capital Advisors in Hollow Way, New York.
U.S. West Texas Intermediate (WTI) light crude (WTI) settled down $7.54 at $66.15 a barrel, and fell further post-settlement, reaching a four-year low of $65.69. The last time the market lost 10 percent in a day was in March 2009.
North Sea Brent LCOc1 finished down $2.43, or 3.3 percent, at $70.15. It fell to as low as $69.78 on the day, a bottom since May 2010. Brent also finished down 18 percent for November for a fifth straight month of declines, or the longest losing streak since the 2008-2009 financial crisis.
Since June, Brent has given up about 40 percent of its value, falling from above $115, as increasing U.S. shale oil output helped create a glut amid sluggish global growth.
Friday's selloff culminated a stunning 24 hours on global crude markets, in near free fall after Saudi Arabia blocked calls from poorer members of the Organization of the Petroleum Exporting Countries to reduce production.
With U.S. markets officially closed for Thursday's Thanksgiving holiday, WTI went down about 8 percent in electronic trading overnight. Losses resumed when the New York Mercantile Exchange reopened, with U.S. crude capitulating just before Friday's close.
The risk flight in oil extended to the stock market, with energy shares on Wall Street taking a hammering despite the broader market closing up for a sixth straight week.
Shares of shale energy firms saw outsized declines, as $70 oil was considered a level at which shale drilling became unprofitable. Denbury Resources (DNR.N), QEP Resources (QEP.N) and Newfield Exploration (NFX.N) all lost more than 15 percent.