AWS casts a ray of strong sunshine on Amazon's profitability

AWS brought in $2.09 billion in sales in the quarter ended Sept. 30, representing a jump of 78 percent over the same period last year. With an operating profit of $521 million -- up from just $98 million a year earlier -- the unit’s operating profit margin was 25 percent for the quarter, up from 21 percent in Q2 and 17 percent in Q1.

Overall, Amazon beat analyst expectations with $25.4 billion in net sales and a profit of $79 million, or 17 cents cents per share. Analysts polled by Thomson Reuters were expecting a loss of 13 cents per share on sales of $24.91 billion.

Shares of the company's stock shot up by as much as 11 percent in extended trading as a result.

Amazon only began breaking out AWS numbers earlier this year, so these are among the first indications the market has seen of the unit's financial performance.

"We're continuing to see a great acceleration in the pace of innovation," said Brian Olsavsky, Amazon's chief financial officer, on the company's earnings call Thursday afternoon.

AWS has launched more than 500 significant new features this year, Olsavsky said, and it has lowered prices eight times since April 2014.

"Customers are really responding," he said. "They like the speed and agility AWS provides, and they like the new features, many of which allow them to lower their costs."

Aurora, for example, was launched earlier this year as a high-performance alternative to the widely used open-source MySQL database.

Nevertheless, it's still early days, Olsavsky acknowledged.

"We enjoy leading this business, and we believe we're adding new services and features at a rate faster than many others," he said. "The growth rate will remain lumpy and bumpy going forward, but we're very encouraged."