FedEx stock is plunging Friday after the logistics giant came up short of earnings expectations and revised its full-year outlook. Here's what you need to know.

The package-delivery giant said reduced demand for priority services and higher operating costs weighed on results.

FedEx missed quarterly estimates and lowered its full-year guidance. Demand was weaker than expected for business-to-business shipping, which is its most profitable segment. The company is in the early stages of a cost-cutting campaign.