U.S. stocks extend losses amid mixed earnings

U.S. stocks traded lower on Friday morning after three days of losses, as investors digested mixed earnings.

By noon, the Dow Jones Industrial Average went down 83.68 points, or 0.47 percent, to 17,648.24. The S&P 500 shed 9.12 points, or 0.43 percent, to 2,093.03. The Nasdaq Composite Index lost 8.82 points, or 0.17 percent, to 5,137.59.

In corporate news, Amazon.com shares jumped over 15 percent in the early trading on Friday, one day after the online retail giant posted an unexpected quarterly profit.

The e-commerce firm's net sales increased 20 percent to 23.18 billion U.S. dollars in the second quarter of 2015, compared with 19.34 billion in the second quarter of 2014. Operating income was 464 million dollars in the second quarter.

Starbucks shares rose 2.12 percent to 57.76 dollars apiece around midday after the world's famous coffee chain reported a better-than-expected quarterly profit.

The company's global comparable store quarterly sales increased 7 percent, driven by a 4-percent rise in traffic. Its quarterly consolidated operating income went up 22 percent to 938.6 million dollars.

Shares of Biogen, however, fell over 18 percent in the morning session after the biotechnology company lowered its full-year guidance. Its second-quarter revenue also missed market estimate.

On the economic front, U.S. sales of new single-family houses in June 2015 were at a seasonally-adjusted annual rate of 482,000, down 6.8 percent from the revised May level of 517,000.

U.S. stocks declined for the third straight session on Thursday as investors meditated on a raft of largely lackluster earnings reports. Endite