The Dow Jones Transportation Average took a 91-point, or 0.9% dive in morning trading Thursday, with 18 of 20 components trading lower, pushed down by concerns over economic growth and prolonged trade disputes. The selloff comes despite the Dow Jones Industrial Average's 53-point, or 0.2% gain, with 18 of 30 components trading higher. The Dow transports' biggest loser was railroad operator Kansas City Southern's stock , which fell 2.0%. Bank of America Merrill Lynch analyst Ken Hoexter said in a recent note to clients that Kansas City Southern is the most exposed to escalating tariffs on imports from Mexico, with FactSet estimating just under half of the company's revenue coming from its Mexico business. Among other Hoexter said have "material" Mexico revenue, shares of Union Pacific Corp. shed 1.2% and Werner Enterprises Inc. slumped 2.4%.