UPS projected a decline in revenue for the current year, with a key factor being plans to phase out more than half of the business it does with Amazon over the next 18 months.

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.

Anxiety over a Chinese startup’s threat to American artificial intelligence dominance faded further Wednesday as investors turned their focus to the Federal Reserve’s rate decision due later in the da