Dow ends choppy day slightly lower; Nasdaq gains

US stocks ended a rocky week on a muted note Friday, with the Dow dipping and Nasdaq advancing as fears about a global economic slowdown due to China tested sentiment. The Dow Jones Industrial Average shed 11.76 points (0.07 percent) at 16,643.01. The broad-based S&P 500 added 1.21 (0.06 percent) at 1,988.87, while the tech-rich Nasdaq Composite Index gained 15.62 (0.32 percent) at 4,828.32.