A decline in shares of UnitedHealth Group Inc. /zigman2/quotes/210453738/composite UNH -0.95% Thursday morning was producing the most severe drag on the blue-chip Dow Jones Industrial Average /zigman2/quotes/210598065/realtime DJIA -0.38% in early action. Shares of UnitedHealth were down 1.8%, or about $4.75 lower at $261.90, translating to a roughly 30-point drag on the price-weighted Dow. The company's shares had hit a low of $257.26 near the open, representing a drag of about 50 points on the Dow. A $1 move in any one of its 30 components of the 123-year-old index equates to a 6.8-point swing. The Dow was down 18 points, or 0.1%, at 27,198. Capping the decline in the Dow was an advance in International Business Machines Corp., which was up 3.2%, delivering a roughly 30-point boost to the Dow. Meanwhile, the S&P 500 index /zigman2/quotes/210599714/realtime SPX -0.32% was off 0.1% at 2,981, with a 0.2% decline for the Nasdaq Composite Index /zigman2/quotes/210598365/realtime COMP -0.40% to reach 8,170. The losses for UnitedHealth come even as the health insurer reported better-than-expected quarterly results and lifted its full-year earnings outlook to $13.95 to $14.15 a share, from its previous forecast of $13.80 to $14.05. Late Wednesday, International Business Machines Corp.'s /zigman2/quotes/203856914/composite IBM +0.53% quarterly results topped estimates.