Amazon on Thursday reported its profits had more than doubled in the past quarter as company founder Jeff Bezos heaped praise on the performance of its Alexa digital assistant.
Net profit more than doubled to $1.9 billion, compared with $749 million a year earlier, for the US online giant which has expanded from retail to video to cloud computing and other services.
Overall revenues for Amazon rose 38 percent from last year to $60.5 billion.
While Amazon offered only limited details on the reasons for growth, Bezos said a big factor was Alexa – the name given to the artificial intelligence program powering its speakers and adopted by makers of cars, appliances and other connected devices.
‘Our 2017 projections for Alexa were very optimistic, and we far exceeded them,’ Bezos said in a statement.
‘We’ve reached an important point where other companies and developers are accelerating adoption of Alexa,’ he said. 
‘There are now over 30,000 skills from outside developers, customers can control more than 4,000 smart home devices from 1,200 unique brands with Alexa, and we’re seeing strong response to our new far-field voice kit for manufacturers.’
Amazon’s success in expanding into new sectors and markets has made Bezos the world’s richest individual, and the last report suggests growth is accelerating.
Shares in Amazon jumped five percent in after-hours trade to $1,464.
One of the big profit centers for Amazon has been its cloud computing division called Amazon Web Services. 
In the fourth quarter, AWS revenues were up 45 percent to $5.1 billion and the unit delivered an operating profit of $1.8 billion.
For Amazon’s North American operations, following the acquisition of grocery chain Whole Foods, revenues rose 42 percent and the division posted an operating profit of $1.7 billion.
The international operations saw an operating loss of $919 million on revenues of $18 billion.