US transportation stocks plunged Monday morning after Amazon.com Inc. announced expanded logistics offerings that will turn it into a major competitor for parcel carriers and air freight companies, and also impact truckers and third-party brokers.

FedEx Corp. shares fell as much as 7.4% in its worst day in more than a year, while fellow rival United Parcel Service Inc. dropped as much as 8.9%. Logistics firms Forward Air Corp. and GXO Logistics Inc. suffered double-digit declines. Several truckers, including Old Dominion Freight Line Inc., fell more than 5%.