Dragged down by declines for shares of American Express and Boeing, the Dow Jones Industrial Average is slumping Tuesday afternoon. Shares of American Express AXP, -8.47% and Boeing BA, -5.08% are contributing to the index’s intraday decline, as the Dow DJIA, -1.76% was most recently trading 726 points (2.1%) lower. American Express’s shares have declined $14.99, or 7.7%, while those of Boeing have fallen $11.84 (5.8%), combining for an approximately 177-point drag on the Dow. Also contributing significantly to the decline are JPMorgan Chase JPM, -3.77%, Dow Inc. DOW, -3.10%, and Visa V, -3.31%. A $1 move in any of the Dow’s 30 components results in a 6.59-point swing.