The Dow Jones Industrial Average is rallying Wednesday afternoon with shares of American Express and Amgen Inc. leading the way for the blue-chip average. The Dow DJIA, +1.37% is trading 488 points (1.8%) higher, as shares of American Express AXP, +2.84% and Amgen Inc. AMGN, +2.14% have contributed about 25% of the index’s intraday rally. American Express’s shares are up $3.01, or 3.1%, while those of Amgen Inc. have gained $6.98 (2.8%), combining for an approximately 66-point boost for the Dow. Also contributing significantly to the gain are UnitedHealth UNH, +2.59%, Goldman Sachs GS, +2.37%, and Salesforce.com Inc. CRM, +1.80%. A $1 move in any one of the 30 components of the benchmark results in a 6.58-point swing.