U.S. stocks opened lower Friday as the U.S. gross domestic product data in the first quarter came in lower than analysts' expectation.

The U.S. real gross domestic product increased at an annual rate of 2.5 percent in the first quarter of 2013, according to the advance estimate released by the U.S. Commerce Department Friday.

Although the figure was better than an anemic 0.4-percent growth in the fourth-quarter of last year, it failed to beat analysts' projection of increasing 3.0 percent.

Amazon.com and Starbucks released mixed quarterly earnings late on Thursday. Amazon reported net income of 82 million U.S. dollars, or 18 cents per share, in the first quarter, both lower than the year-ago level but topping analysts' estimates by a large margin. Its revenue in the quarter fell 22 percent to 16.07 billion dollars. Shares of Amazon plunged 4.46 percent to 262.46 dollars a share.

Meanwhile, Starbucks made a profit of 390.4 million dollars on revenue of 3.6 billion dollars in its fiscal second quarter, higher than those of the same period of last year and was slightly better than market forecast.

However, its earnings guidance for the next quarter was below forecast. Shares of the world's biggest coffee chain dropped 0.81percent to 60.01 dollars a share.

According to Thomson Reuters data, nearly half of the S&P 500 companies have reported their quarterly earnings so far, among which a little more than two-thirds of them reported earnings above analysts' expectations.

Analysts predicted earnings growth of 3.6 percent during the quarter, up from a forecast of rising 1.5 percent at the beginning of April.

The Dow Jones Industrial Average dropped 6.22 points, or 0.04 percent, to 14,694.58 points. The S&P 500 slid 3.51 points, or 0.22 percent, to 1,581.65 points. The Nasdaq Composite dipped 8.94 points, or 0.27 percent, to 3,281.05 points. Endi