Crude-oil futures fell Tuesday, giving up part of the prior day’s 4% gain and barely holding above the five-year lows hit Friday.

On the New York Mercantile Exchange, crude futures for delivery in January declined $2.12, or 3.1%, to settle at $66.88 a barrel. Oil futures have been down for five out of the past six sessions. January Brent crude shed $2, or 2.8%, to $70.54 a barrel. Brent is down for six out of the last seven sessions. Commodity and financial markets are still reeling from the recent plunge in oil prices, which have lost 38% of their value since a peak in June. Investors are bracing for spending cuts by global oil majors as they adjust to a new low-price environment.

Oil prices have slumped to five-year lows after the Organization of the Petroleum Exporting Countries on Thursday decided to leave its oil output unchanged. OPEC has ceded no ground to competitors, including American shale. But the group will be bruised as many of its member countries face prices below break-even budgets, with oil at around $70 a barrel, Dan K. Eberhart, chief executive of U.S. oil-field-services company Canary LLC said. U.S. drillers can expand oil production in the face of falling oil prices as they have become more efficient at coaxing energy from tight rocks, Eberhart said at the OSEA 2014 energy conference in Singapore. “In an amazing feat of engineering and economics, lift costs have been driven down as much as $30 per barrel since 2012,” he said. Lift cost is the cost of bringing oil to the surface from its source.

Meanwhile, some analysts have cautioned against assuming that oil prices have found a bottom. “Without a bullish fundamental shock to help the market make and sustain a V-shaped price recovery, we’d want to see a more thorough confirmation of a technical base of support before declaring that anything more than the latest trading bottom has been established,” said Tim Evans, energy futures specialist for Citi, in a note late Monday. Other analysts are cutting their oil price forecasts in the aftermath of OPEC’s meeting last week.

Societe Generale slashed its oil price forecast for Brent crude by $20 a barrel for 2015 and 2016, and expects the global benchmark to average $70 a barrel in the next two years. It also cut its Nymex WTI crude forecast by $17 in 2015 and $16 in 2016, to average $65 in both years. “We estimate the costs for most U.S. shale oil at $65 WTI, if not lower. In recent days, after last week’s OPEC meeting, crude prices have already approached those levels, and we expect them to stay there for an extended period of two years,” said Michael Wittner, head of oil research at Societe Generale.