The Dow Jones Industrial Average was trading sharply higher midday Tuesday, putting blue chips on track to book the best one-day gain since March. The Dow (DJIA) was up about 492 points, or 2%, at 25,739. Tuesday's rally was partly on the back of a surge in shares of component UnitedHealth Group Inc. (UNH) which was delivering a roughly 70-point jolt to the price-weighted equity gauge.


Share rises for UnitedHealth come after the health-care company raised its full-year earnings outlook and said it continues to see growth in health-care plan membership and premiums. Meanwhile, the S&P 500 indexSPX, +1.82% was climbing 2% at 2,804 and the Nasdaq Composite IndexCOMP, +2.49% advanced by 2.6% to 7,620. Wall Street investors appear to be focusing upbeat earnings, including those from Goldman Sachs Group Inc.GS, +2.62% Johnson & Johnson JNJ, +1.46% and Morgan Stanley MS, +5.51%