Amazon has rapidly built up its own logistics empire since a 2013 holiday fiasco left its packages stranded in the hands of outside carriers. The company now oversees thousands of last-mile delivery companies that deliver packages exclusively for Amazon, as well as a budding in-house network of planes, trucks and ships. By some estimates, Amazon's in-house logistics operations have grown to rival or exceed the size of major carriers.
UPS has, for its part, taken more aggressive cost-control measures, including catering to more profitable delivery customers. In recent quarters, UPS has benefited from an influx of volume from bargain retailers Temu and Shein, which have rapidly gained popularity in the U.S.