Merck fell $6.56, or 15%, to $37.95 and Schering-Plough declined $5.06, or 26%, to $15.41 after medical researchers said the companies' joint anti-cholesterol drug, Vytorin, failed to improve heart disease. The researchers' findings, published by the New England Journal of Medicine, urged a return to more established treatments for cholesterol. Merck is one of the 30 stocks that comprise the Dow industrials and, as a result, dragged on the blue chips.
Citigroup rose 59 cents, or 2.8%, to $21.42 after announcing plans to split its consumer banking unit from its credit card business as part of a broader reorganization to cut costs and simplify the large financial institution's structure. The company suffered billions of dollars in losses from investments in poor-quality mortgages.
The Russell 2000 index of smaller companies rose 4.79, or 0.70%, to 687.97.
Overseas, Japan's Nikkei stock average fell 2.30%. Britain's FTSE 100 closed up 0.16%, Germany's DAX index fell 0.28%, and France's CAC-40 rose 0.24%.