Shares of United Parcel Service plunged more than 15% Thursday after the company issued weak revenue guidance for the year and said it planned to cut deliveries for Amazon, its largest customer, by more than half.

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.

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.