Shares of Boeing and Dow Inc. are trading lower Tuesday afternoon, leading the Dow Jones Industrial Average selloff. The Dow DJIA, -0.94% was most recently trading 339 points, or 1.0%, lower, as shares of Boeing BA, -4.27% and Dow Inc. DOW, -4.27% have contributed to the blue-chip gauge’s intraday decline. Boeing’s shares are down $11.16, or 4.4%, while those of Dow Inc. are off $2.76 (4.4%), combining for an approximately 92-point drag on the Dow. Also contributing significantly to the decline are Caterpillar CAT, -3.75%, Intel INTC, -3.15%, and American Express AXP, -2.92%. A $1 move in any one of the 30 components of the index results in a 6.58-point swing.