Amazon.com swung to an unexpected quarterly profit on higher sales in North America, its popular Prime subscription service and growing demand for its Web services sending the online retailer’s shares up more than 17 per cent.

Amazon also forecast third-quarter revenue above estimates. Sales in North America, the company’s biggest market, rose 25.5 per cent to $13.8 billion in the second quarter from a year earlier, helped by strong demand for electronics and general merchandise.

Cloud-computing revenue soared 81.5 per cent to $1.82 billion, accounting for nearly 8 per cent of the quarter’s revenue.

The company forecast net sales would grow 13 per cent to 24 per cent, to a range of $23.3 billion to $25.5 billion, in the third quarter. This is well above analysts’ consensus estimate of $23.89 billion.

Amazon estimated an operating loss of $480 million to an operating income of $70 million for the third quarter. It reported a profit of $92 million, or 19 cent per share, for the second quarter ended June 30th, compared with a loss of $126 million, or 27 cent per share, a year earlier. Revenue rose 19.9 per cent to $23.19 billion. Analysts on average had expected a loss of 14 cent per share and revenue of $22.39 billion.