In commodities trading, the price of oil rose 54 cents, or 0.6 percent, to $95.14 a barrel. The price of gold fell $3.50, or 0.3 percent, to $1,281.10 an ounce.
Among stocks making big moves:
— ViroPharma jumped $10.04, or 26 percent, to $49.42 after the company agreed to be acquired by drugmaker Shire PLC.
— Transocean rose $1.92, or 3.6 percent, to $55.37 after the company said it had agreed to settle a months-long proxy fight with billionaire investor and minority shareholder Carl Icahn. The company will pay a $3-a-share dividend and reduce the size of its board.
— Best Buy rose $1.92, or 4.5 percent, to $44.33 after an analyst at UBS lifted his rating on the stock to "buy" from "neutral" and raised his price target on the stock in anticipation of better earnings. Best Buy has risen 274 percent this year, making it the best performer in the S&P 500 index.