BP said on Tuesday that lower refining margins would hurt its fourth-quarter profit by $100 million to $300 million and that it expects oil trading to be weak.

BP forecasts that weaker realized refining margins will dent the Q4 earnings by up to $300 million. Refinery turnaround activity is also set to have a higher impact for the fourth quarter compared to the third quarter.

KEY TAKEAWAYS BP stock is falling in premarket trading Tuesday after the British oil giant said it expects to book impairments of between $1.0 billion to $2.0 billion in the fourth quarter.BP also forecast "weaker" fourth-quarter refining margins.

British oil major BP said on Tuesday that it expects its fourth-quarter upstream production to be lower than the third quarter. The forecast is due to lower output in oil production and operations, and in gas and low carbon energy.