NEW YORK (AP) -- Earnings gains from Microsoft and other big U.S. companies are pushing the stock market higher in early trading.
Microsoft led the Dow Jones industrial average higher after reporting higher sales of tablet computers.
The Dow was up 34 points, or 0.2 percent, at 15,543 in the first half-hour of trading Friday. The Standard & Poor's 500 index was up four points, or 0.3 percent, at 1,756. The Nasdaq composite rose 29 points, or 0.7 percent, to 3,958.
Microsoft beat analysts' forecasts for revenue and earnings, giving hope to investors that the company's shift to devices and services from PC-based software will be successful. Microsoft rose $2.22 to $35.94, a gain of more than 6 percent, after reporting a 17 percent increase in third quarter net income.
Amazon.com and Zynga were both up more than 6 percent on surprisingly strong quarterly numbers, too.
All three major indexes are up more than 18 percent since the start of the year as a slowly recovering U.S. economy, higher corporate earnings and continued economic stimulus from the Federal Reserve encourage investors to keep buying. The tech-heavy Nasdaq is at a 13-year high.
Amazon.com was up $29.70, or 9 percent, to $362 as investors continue to shrug off its losses. The online retailer reported that revenue rose 24 percent to $13.8 billion in the third quarter, more than financial analysts had expected.
Zynga surged 13 percent after the Internet gaming company reported it had cut losses in the third quarter. The maker of "Farmville" and "Mafia Wars" is trying to appeal more to users of smartphones and tablet computers under a new CEO.