UPS CEO Carol Tome said on a call with investors that Amazon is UPS’ largest customer, but it is not the company’s most profitable customer.

United Parcel Service on Thursday forecast downbeat 2025 revenue as it cuts back deliveries for its largest customer, Amazon.com , and grapples with stubbornly soft demand for lucrative overnight service and commercial shipments.

United Parcel Service Inc. shares plunged after the company projected annual revenue well below expectations, telling investors that a long-awaited rebound in demand for its parcel services won’t arrive this year and prompting it to slash its low-margin business with Amazon.