(Close): US stock indexes edged higher on Monday, with the S&P 500 closing at another record high.
The S&P 500 inched 1.8 points higher to 1,951.27, while The Dow Jones industrial average rose 18.82 points to 16,943.10 and the Nasdaq Composite added 14.84 points to 4,336.24.
Merck said it would buy Idenix Pharmaceuticals in a deal valued at about $3.85bn (£2.29bn) to strengthen its hepatitis C drugs portfolio.
Idenix shares soared 242%.
McDonald's, the world's largest hamburger chain said U.S. sales declined 1% at locations open at least 14 months. The fast-food chain has been struggling to boost sales amid heightened competition and changing eating habits.
McDonald's shares fell less than 0.6%.
Tyson Foods won a bidding war for Hillshire Brands, the maker of Jimmy Dean sausages and Ball Park hot dogs, with a $63 per share offer. Hillshire shares rose 5.3%.
