Updated from 2:20 p.m. EST
Crude oil prices fell back to the $49-a-barrel level Monday, after a one-day bounce.
The December futures contract closed 52 cents lower at $49.09 in Nymex floor trading, having fallen about 11% to a six-week low in the previous eight sessions.
After months of almost constant concern about short-term supplies, traders appear less bullish about the market.
U.S. production has been recovering from a severe disruption in the Gulf of Mexico, where Hurricane Ivan upset rigs and pipelines in September.
As recently as 12 days ago, prices were at a record high of more than $55 per barrel, part of a 65% gain this year.