Amazon posts quarterly loss; shares dip

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Amazon reported earnings that fell short of Wall Street forecasts, as it continued to spend heavily on technology and content, and issued a cautious revenue outlook.

The online retailer's net sales rose 22 percent to $15.7 billion in the second quarter from $12.83 billion in the year-earlier period.

The company's operating margin was just 0.5 percent, as its operating expenses jumped 23 percent. Amazon has been spending heavily to expand internationally and beef up its Web services business. Spending on technology and new content jumped 46 percent from a year earlier. It posted an operating margin of 1.1 percent in the first quarter.

Amazon's international sales growth also slowed in the quarter, to 16 percent from 31 percent growth a year earlier.

For the third quarter, Amazon is forecasting net sales of $15.45 billion to $17.15 billion, representing growth of between 12 percent and 24 percent. The Street was expecting net revenue of $16.98 billion for the third quarter.

"Amazon's still largely a revenue growth story and if we're starting to see some slowing revenue growth that could be a concern for investors," Aaron Kessler, an analyst at Raymond James, told CNBC.

The net loss was 2 cents per share, after a profit of a penny a share a year ago.

(Read more: Buying a Picasso on Amazon? Not so crazy anymore)

Analysts expected the online retailer to post earnings of 5 cents per share on sales of $15.73 billion, according to estimates from Thomson Reuters.

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