Oil futures ended with small gains Thursday, but only after the U.S. benchmark sank below the $44-a-barrel level for the first time in nearly six years in a trading environment shadowed by a rapidly growing glut of crude. Light, sweet crude for March delivery on the New York Mercantile Exchange rose 8 cents, or 0.2%, to close at $44.53 a barrel. It was a choppy trading session, with the contract earlier dipping as low as $43.58, its lowest level since March 2009. The price action follows a 3.9% slide from Wednesday, which was triggered by bearish inventory data. ICE Brent crude, the global oil benchmark, gained ground, with the March contract rising 66 cents, or 1.4%, to settle at $49.13 a barrel.

The U.S. Energy Information Administration on Wednesday said U.S. oil supplies rose by 8.9 million barrels in the week ended Jan. 23, higher than the increase of around 3.5 million barrels expected by analysts polled by Platts. At 406.7 million barrels, U.S. inventories are at their highest since 1924. With the oil market in “contango” — a condition when deferred futures prices are at a premium to nearby futures — there is a strong incentive for players to store oil, adding to the buildup in U.S. inventories, analysts noted. “In conjunction with ongoing high levels of U.S. oil production – which last week achieved a 28-year high of 9.2 million barrels a day – this suggests that the inventory build will continue and oil prices will fall further in the coming weeks,” wrote strategists at Commerzbank in Frankfurt. “The only glimmer of hope in yesterday’s inventory report were the sharp falls in gasoline and distillate stocks on the back of robust demand. That said, this will hardly be sufficient to prevent crude oil stocks from swelling even further.”

The rise in inventories is a reflection of the recent slump in oil prices, caused by a global supply glut and weakening demand. The almost 60% drop in prices since the summer has taken its toll on oil producers, with several companies announcing cost-cutting strategies and layoffs. 

On Thursday, Anglo-Dutch oil major Royal Dutch Shell PLC reported a rise in fourth-quarter earnings, amid the slump in oil prices. Analysts have been expecting the price slide to weigh on sector earnings, but for Shell, however, it was forecast to suffer less of a year-over-year impact than its rivals because its 2013 fourth-quarter earnings were dragged by spending and refining issues.