US stocks fell Friday, hurt by weak corporate results and a slide in Merck & Co, after news that its osteoporosis drug could lose its patent earlier than expected. Merck said on Friday a federal judge has ruled that its osteoporosis drug Fosamax, its second-biggest product, could lose its patent in 2008 instead of the company's timetable of 2018. The drug maker also said that US securities regulators have started a formal investigation into the company's handling of its withdrawn arthritis drug Vioxx. Merck's shares plunged 10 percent to $28.
The Dow Jones industrial average was down 61.11 points, or 0.59 percent, at 10,406.14. The Standard & Poor's 500 Index was down 6.80 points, or 0.58 percent, at 1,167.95. The technology-laced Nasdaq Composite Index was down 17.62 points, or 0.86 percent, at 2,029.69.