Amazon has fallen short of analyst expectations for its second-quarter earnings, despite posting a 10% year-on-year increase to US$147.98 billion in net sales.

The figure came close to a billion dollars under the US$148.78 billion consensus analyst estimate, with the tech giant's shares slipping as much as 8% in after-hours trading in New York on Thursday evening.

Net income was a more positive story, growing to US$13.5 billion, exceeding analysts' forecasts of US$11 billion and well ahead of the US$6.7 billion of net income recorded for Q2 2023.

When excluding the $1.0 billion unfavourable impact from year-over-year changes in foreign exchange rates, net sales in Q2 were up 11% compared to Q2 2023. Anticipation of similar impacts in the next quarter saw Q3 guidance reduced to between US$154 billion and US$158.5 billion.

The company's cloud division, Amazon Web Services (AWS), also saw strong growth, lifting sales 19% to $26.3 billion ahead of analyst forecasts of $US26 billion. However, margins on the AWS unit narrowed 2 points down to 36%, as the company invests in AI infrastructure.

"We’re continuing to make progress on a number of dimensions, but perhaps none more so than the continued reacceleration in AWS growth," said Amazon President & CEO, Andy Jassy. "As companies continue to modernize their infrastructure and move to the cloud, while also leveraging new Generative AI opportunities, AWS continues to be customers’ top choice as we have much broader functionality, superior security and operational performance, a larger partner ecosystem, and AI capabilities like SageMaker for model builders, Bedrock for those leveraging frontier models, Trainium for those where the cost of compute for training and inference matters, and Q for those wanting the most capable GenAI assistant for not just coding, but also software development and business integration."

2024 marked Amazon's 10th Prime Day shopping event, and also saw the company introduce multiple AI-powered features for consumers, including shopping assistant Rufus for all U.S. mobile customers, playlist generator Maestro for Amazon Music, and a new search experience for Fire TV.