FedEx just announced earnings and gave lower guidance going forward. The stock is down 9% in after-hours trading. Not a good sign for the overall economy when a huge transportation stock like that is guiding lower.
Now, if UPS announces lower traffic, that is way more severe since they're over twice the size of FDX.
Fed ex actually has more employees than UPS. UPS has a bigger market cap but makes far less money with that size of market cap then FedEx does.