Shares of UnitedHealth and American Express are trading lower Friday morning, sending the Dow Jones Industrial Average into negative territory. Shares of UnitedHealth /zigman2/quotes/210453738/composite UNH +1.06% and American Express /zigman2/quotes/203805826/composite AXP -0.56% are contributing to the blue-chip gauge's intraday decline, as the Dow /zigman2/quotes/210598065/realtime DJIA -0.04% was most recently trading 71 points (0.3%) lower. UnitedHealth's shares are off $5.79 (2.4%) while those of American Express have fallen $1.68 (2.2%), combining for a roughly 51-point drag on the Dow. Other components contributing significantly to the decline include Walt Disney /zigman2/quotes/203410047/composite DIS +0.16% , Nike /zigman2/quotes/203439053/composite NKE -0.54% , and 3M /zigman2/quotes/205029460/composite MMM +0.43% . A $1 move in any of the index's 30 components equates to a 6.78-point swing.