New York (CNN Business) Crude oil prices are in free-fall as fears of a supply glut mount.

US oil prices plummeted 7% to a one-year low of $55.69 a barrel on Tuesday. It was crude's worst day since September 2015.

"Bearish sentiment has seized control of the oil markets," said Clay Seigle, managing director of oil at Genscape.

It's been a huge reversal considering oil spiked to a four-year high of $76 a barrel as recently as early October.

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