The 13.9% plunge in FedEx Corp.'s stock is the main reason the Dow Jones Transportation Average is tumbling 170 points, or 1.6%; that is much worse than the performance of its sister index the Dow Jones Industrial Average , which lost 56 points, or 0.2%. FedEx stock's price drop of $24.07, following disappointing quarterly results and a lowered full-year outlook, accounted for about 147 points of the Dow transports' price decline. Add the $2.52, or 2.1% decline in United Parcel Service Inc. shares in sympathy, and the FedEx-related selloff was shaving 162 points off the Dow transports.