Amazon rose $15.32, or 7 percent, to $238.24 despite a smaller-than-expected quarterly profit and a prediction for smaller-than-expected holiday revenue.
Among other companies making big moves, cable TV provider Comcast jumped $1.20, or 3.3 percent, to $37.56 after reporting that its income more than doubled in the latest quarter. Revenue was higher than analysts were expecting, and more customers signed up for premium services like high-definition video recorders.
Varian Medical Systems jumped $8.83, or 15 percent, to $66.93, the biggest increase in the S&P 500 index. The company, which sells medical imaging equipment and radiation-emitting devices for treating tumors, reported a 20 percent rise in income because of higher sales of devices.
On its first day of trading, dairy company WhiteWave Foods lost 25 cents to $16.75, down from its initial public offering price of $17, after rising as high as $19.17 earlier.The yield on the 10-year Treasury note fell to 1.75 percent from 1.82 percent on Thursday.