Oil prices have slid Movement.down.loss due to concern Negative_sentiment about weakening Slow.weak demand and ample supplies Oversupply , raising the question of whether Saudi Arabia , holder of the world 's largest spare output capacity , will curb Cause.movement.down.loss output .

Demand worries Negative_sentiment flipped the oil market into a contango last week , a market structure where prices for near-term contracts are lower than those for later contracts , indicating ample supplies Oversupply .