This seems... incorrect? http://www.fedex.com/us/about/overview/companies/express/Exp... indicates that they own 696 aircraft, and https://www.reuters.com/article/us-airline-fedex-orders/fede... says that they just bought 50 more in 2015. No mentions of a lease agreement here. In fact, according to Wikipedia, for smaller aircraft FedEx operates a dry lease business where they lease their fleet out to contractors to deliver certain routes:

    In the United States (along with Morningstar Air Express in Canada), FedEx Express operates FedEx Feeder (and for Morningstar, mainline FedEx service) on a dry lease program where the contractor will lease the aircraft from the FedEx fleet and provide a crew to operate the aircraft solely for FedEx