U.S. crude-oil futures marked their first decline in five sessions on Wednesday, plunging by almost 9% to settle below the $50 mark as the nation’s stockpiles climbed more than expected.

West Texas Intermediate crude for March delivery slid $4.60, or 8.7%, to settle at $48.45 a barrel on the New York Mercantile Exchange. Oil was trading around $50.90 before the supply data were released. The retreat took a bite out of the contract’s nearly 20% rebound that had begun on Thursday on hope that a cut in U.S. production would whittle down crude stockpiles. But such hopes were dampened, at least for the short term. On Wednesday, the U.S. Energy Information Administration said crude stockpiles rose 6.3 million barrels for the week ended Jan. 30. Analysts polled by Platts forecast a climb of 2.8 million barrels. “Crude stocks have now built by 30 million barrels in the last four weeks, and will continue to through the first quarter — as is the seasonal trend,” said Matt Smith, commodity analyst at Schneider Electric.

American Petroleum Institute data released after the Nymex close on Tuesday showed weekly inventories rising by 6.1 million barrels. U.S. traders are “looking to lock in some profits after the last few trading days, and the meteoric rise in oil prices,” said Kevin Kerr, president of Kerr Trading International. “The EIA report reflected a significant build in supplies [and] coupled with solid [gasoline] supplies, signaled to traders to take some profits off the table.” Looking ahead, “traders need to buckle up for some serious volatility,” he said, adding that he expects prices to “stair-step higher” — up to about $65 to $70 by late in the third quarter.

EIA data also showed gasoline supplies rose by 2.3 million barrels, while distillate stockpiles climbed by 1.8 million barrels. Analysts surveyed by Platts were looking for a decline of 800,000 barrels for gasoline stockpiles and a fall of 2.1 million barrels for distillates, which include heating oil.