Shares of Caterpillar and Johnson & Johnson are retreating Friday afternoon, sending the Dow Jones Industrial Average into negative territory. Shares of Caterpillar CAT, -2.40% and Johnson & Johnson JNJ, -1.44% have contributed to the index’s intraday decline, as the Dow DJIA, -0.11% was most recently trading 34 points (0.1%) lower. Caterpillar’s shares have dropped $5.01, or 2.2%, while those of Johnson & Johnson are down $2.35 (1.4%), combining for an approximately 48-point drag on the Dow. Also contributing significantly to the decline are UnitedHealth UNH, -1.07%, Amgen Inc. AMGN, -0.88%, and Procter & Gamble PG, -0.74%. A $1 move in any of the index’s 30 components results in a 6.58-point swing.