Shares of American Express and Boeing are seeing declines Wednesday morning, sending the Dow Jones Industrial Average into a slump. The Dow /zigman2/quotes/210598065/realtime DJIA +2.17% was most recently trading 675 points lower (-3.1%), as shares of American Express /zigman2/quotes/203805826/composite AXP +5.59% and Boeing /zigman2/quotes/208579720/composite BA +5.24% are contributing to the blue-chip gauge's intraday decline. American Express's shares are off $5.03 (5.9%) while those of Boeing are down $7.52 (5.0%), combining for a roughly 85-point drag on the Dow. Dow Inc. /zigman2/quotes/203121064/composite DOW +7.39% , JPMorgan Chase /zigman2/quotes/205971034/composite JPM +7.10% , and Merck /zigman2/quotes/209956077/composite MRK +1.17% are also contributing significantly to the decline. A $1 move in any one of the 30 components of the index equates to a 6.78-point swing.