Buoyed by strong returns for shares of Visa and Amgen Inc., the Dow Jones Industrial Average is trading up Wednesday morning. The Dow DJIA, +0.28% is trading 88 points (0.3%) higher, as shares of Visa V, +2.12% and Amgen Inc. AMGN, +0.91% are contributing to the index’s intraday rally. Visa’s shares are up $5.37, or 2.4%, while those of Amgen Inc. have gained $2.37, or 1.0%, combining for a roughly 51-point boost for the Dow. Merck MRK, +0.62%, Boeing BA, +1.12%, and IBM IBM, +0.83% are also contributing significantly to the gain. A $1 move in any of the benchmark’s 30 components results in a 6.58-point swing.