United Parcel Service Inc. suffered its biggest one-day share drop after shocking the market by slashing business with the world’s largest online retailer.

United Parcel Service will halve its Amazon package volume to bolster its profitability, but the unexpected move sent the stock tumbling Thursday. Why it matters: UPS gets nearly 12% of its revenue from Amazon deliveries,

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.

Shares of United Parcel Service suffered their worst day ever on Thursday, after the package-delivery giant announced an agreement that would cut its business with Amazon.com Inc., its largest customer,